Harmonizome 3.0

POLG alternative reading frame

This gene uses the same transcript as the POLG gene but has a CUG start codon and an alternate reading frame that makes a 260 aa protein. This protein is distinct from POLG isoforms and may interact with P32 (also known as C1QBP), a mitochondrial matrix protein thought to be involved in the expression of mitochondrial genome-encoded proteins. POLGARF protein may bind P32 and sequester it in the nucleolus. Interestingly, some disease-causing mutations thought to be in POLG may instead be associated with POLGARF. [provided by RefSeq, May 2022]

integrin, alpha X (complement component 3 receptor 4 subunit)

This gene encodes the integrin alpha X chain protein. Integrins are heterodimeric integral membrane proteins composed of an alpha chain and a beta chain. This protein combines with the beta 2 chain (ITGB2) to form a leukocyte-specific integrin referred to as inactivated-C3b (iC3b) receptor 4 (CR4). The alpha X beta 2 complex seems to overlap the properties of the alpha M beta 2 integrin in the adherence of neutrophils and monocytes to stimulated endothelium cells, and in the phagocytosis of complement coated particles. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Nov 2013]

integrin, alpha M (complement component 3 receptor 3 subunit)

This gene encodes the integrin alpha M chain. Integrins are heterodimeric integral membrane proteins composed of an alpha chain and a beta chain. This I-domain containing alpha integrin combines with the beta 2 chain (ITGB2) to form a leukocyte-specific integrin referred to as macrophage receptor 1 ('Mac-1'), or inactivated-C3b (iC3b) receptor 3 ('CR3'). The alpha M beta 2 integrin is important in the adherence of neutrophils and monocytes to stimulated endothelium, and also in the phagocytosis of complement coated particles. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Mar 2009]

complement factor H

This gene is a member of the Regulator of Complement Activation (RCA) gene cluster and encodes a protein with twenty short consensus repeat (SCR) domains. This protein is secreted into the bloodstream and has an essential role in the regulation of complement activation, restricting this innate defense mechanism to microbial infections. Mutations in this gene have been associated with hemolytic-uremic syndrome (HUS) and chronic hypocomplementemic nephropathy. Alternate transcriptional splice variants, encoding different isoforms, have been characterized. [provided by RefSeq, Oct 2011]

complement factor I

This gene encodes a serine proteinase that is essential for regulating the complement cascade. The encoded preproprotein is cleaved to produce both heavy and light chains, which are linked by disulfide bonds to form a heterodimeric glycoprotein. This heterodimer can cleave and inactivate the complement components C4b and C3b, and it prevents the assembly of the C3 and C5 convertase enzymes. Defects in this gene cause complement factor I deficiency, an autosomal recessive disease associated with a susceptibility to pyogenic infections. Mutations in this gene have been associated with a predisposition to atypical hemolytic uremic syndrome, a disease characterized by acute renal failure, microangiopathic hemolytic anemia and thrombocytopenia. Primary glomerulonephritis with immune deposits and age-related macular degeneration are other conditions associated with mutations of this gene. [provided by RefSeq, Dec 2015]

complement factor D (adipsin)

This gene encodes a member of the S1, or chymotrypsin, family of serine peptidases. This protease catalyzes the cleavage of factor B, the rate-limiting step of the alternative pathway of complement activation. This protein also functions as an adipokine, a cell signaling protein secreted by adipocytes, which regulates insulin secretion in mice. Mutations in this gene underlie complement factor D deficiency, which is associated with recurrent bacterial meningitis infections in human patients. Alternative splicing of this gene results in multiple transcript variants. At least one of these variants encodes a preproprotein that is proteolytically processed to generate the mature protease. [provided by RefSeq, Nov 2015]

complement factor B

This gene encodes complement factor B, a component of the alternative pathway of complement activation. Factor B circulates in the blood as a single chain polypeptide. Upon activation of the alternative pathway, it is cleaved by complement factor D yielding the noncatalytic chain Ba and the catalytic subunit Bb. The active subunit Bb is a serine protease which associates with C3b to form the alternative pathway C3 convertase. Bb is involved in the proliferation of preactivated B lymphocytes, while Ba inhibits their proliferation. This gene localizes to the major histocompatibility complex (MHC) class III region on chromosome 6. This cluster includes several genes involved in regulation of the immune reaction. Polymorphisms in this gene are associated with a reduced risk of age-related macular degeneration. The polyadenylation site of this gene is 421 bp from the 5' end of the gene for complement component 2. [provided by RefSeq, Jul 2008]

complement factor properdin

This gene encodes a plasma glycoprotein that positively regulates the alternative complement pathway of the innate immune system. This protein binds to many microbial surfaces and apoptotic cells and stabilizes the C3- and C5-convertase enzyme complexes in a feedback loop that ultimately leads to formation of the membrane attack complex and lysis of the target cell. Mutations in this gene result in two forms of properdin deficiency, which results in high susceptibility to meningococcal infections. Multiple alternatively spliced variants, encoding the same protein, have been identified.[provided by RefSeq, Feb 2009]

complement component 4B (Chido blood group)

This gene encodes the basic form of complement factor 4, and together with the C4A gene, is part of the classical activation pathway. The protein is expressed as a single chain precursor which is proteolytically cleaved into a trimer of alpha, beta, and gamma chains prior to secretion. The trimer provides a surface for interaction between the antigen-antibody complex and other complement components. The alpha chain may be cleaved to release C4 anaphylatoxin, a mediator of local inflammation. Deficiency of this protein is associated with systemic lupus erythematosus. This gene localizes to the major histocompatibility complex (MHC) class III region on chromosome 6. Varying haplotypes of this gene cluster exist, such that individuals may have 1, 2, or 3 copies of this gene. In addition, this gene exists as a long form and a short form due to the presence or absence of a 6.4 kb endogenous HERV-K retrovirus in intron 9. [provided by RefSeq, May 2020]

integrin, alpha X (complement component 3 receptor 4 subunit) pseudogene

integrin, beta 2 (complement component 3 receptor 3 and 4 subunit)

This gene encodes an integrin beta chain, which combines with multiple different alpha chains to form different integrin heterodimers. Integrins are integral cell-surface proteins that participate in cell adhesion as well as cell-surface mediated signalling. The encoded protein plays an important role in immune response and defects in this gene cause leukocyte adhesion deficiency. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Dec 2014]

complement component 1, q subcomponent binding protein

The human complement subcomponent C1q associates with C1r and C1s in order to yield the first component of the serum complement system. The protein encoded by this gene is known to bind to the globular heads of C1q molecules and inhibit C1 activation. This protein has also been identified as the p32 subunit of pre-mRNA splicing factor SF2, as well as a hyaluronic acid-binding protein. [provided by RefSeq, Jul 2008]

complement component 8, alpha polypeptide

C8 is a component of the complement system and contains three polypeptides, alpha, beta and gamma. This gene encodes the alpha subunit of C8. C8 participates in the formation of the membrane attack complex (MAC). The MAC assembles on bacterial membranes to form a pore, permitting disruption of bacterial membrane organization. Mutations in this gene cause complement C8 alpha-gamma deficiency. [provided by RefSeq, Nov 2008]

complement component 8, beta polypeptide

This gene encodes one of the three subunits of the complement component 8 (C8) protein. C8 is composed of equimolar amounts of alpha, beta and gamma subunits, which are encoded by three separate genes. C8 is one component of the membrane attack complex, which mediates cell lysis, and it initiates membrane penetration of the complex. This protein mediates the interaction of C8 with the C5b-7 membrane attack complex precursor. In humans deficiency of this protein is associated with increased risk of meningococcal infections. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jun 2013]

complement component 8, gamma polypeptide

The protein encoded by this gene belongs to the lipocalin family. It is one of the three subunits that constitutes complement component 8 (C8), which is composed of a disulfide-linked C8 alpha-gamma heterodimer and a non-covalently associated C8 beta chain. C8 participates in the formation of the membrane attack complex (MAC) on bacterial cell membranes. While subunits alpha and beta play a role in complement-mediated bacterial killing, the gamma subunit is not required for the bactericidal activity. [provided by RefSeq, Jul 2011]

CD46 molecule, complement regulatory protein pseudogene 1

complement component (3b/4b) receptor 1-like

Acts upstream of or within regulation of complement activation and regulation of complement-dependent cytotoxicity. Part of receptor complex. [provided by Alliance of Genome Resources, Mar 2025]

CD55 molecule, decay accelerating factor for complement (Cromer blood group)

This gene encodes a glycoprotein involved in the regulation of the complement cascade. Binding of the encoded protein to complement proteins accelerates their decay, thereby disrupting the cascade and preventing damage to host cells. Antigens present on this protein constitute the Cromer blood group system (CROM). Alternative splicing results in multiple transcript variants. The predominant transcript variant encodes a membrane-bound protein, but alternatively spliced transcripts may produce soluble proteins. [provided by RefSeq, Jul 2014]

CD59 molecule, complement regulatory protein

This gene encodes a cell surface glycoprotein that regulates complement-mediated cell lysis, and it is involved in lymphocyte signal transduction. This protein is a potent inhibitor of the complement membrane attack complex, whereby it binds complement C8 and/or C9 during the assembly of this complex, thereby inhibiting the incorporation of multiple copies of C9 into the complex, which is necessary for osmolytic pore formation. This protein also plays a role in signal transduction pathways in the activation of T cells. Mutations in this gene cause CD59 deficiency, a disease resulting in hemolytic anemia and thrombosis, and which causes cerebral infarction. Multiple alternatively spliced transcript variants, which encode the same protein, have been identified for this gene. [provided by RefSeq, Jul 2008]

complement component 1, q subcomponent binding protein, pseudogene 1

complement component 1, q subcomponent binding protein, pseudogene 2

complement component 1, q subcomponent binding protein, pseudogene 3

complement component 4 binding protein, alpha pseudogene 3

complement component 4 binding protein, alpha pseudogene 2

complement component 1, r subcomponent-like

Predicted to enable serine-type endopeptidase activity. Predicted to be involved in zymogen activation. Located in extracellular exosome. [provided by Alliance of Genome Resources, Mar 2025]

complement component 5a receptor 2

This gene encodes a G-protein coupled receptor 1 family member involved in the complement system of the innate immune response. Unlike classical G-protein coupled receptors, the encoded protein does not associate with intracellular G-proteins. It may instead modulate signal transduction through the beta-arrestin pathway, and may alternatively act as a decoy receptor. This gene may be involved in coronary artery disease and in the pathogenesis of sepsis. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Nov 2012]

complement component 5a receptor 1

Enables G protein-coupled receptor activity and complement component C5a receptor activity. Involved in several processes, including complement component C5a signaling pathway; mRNA transcription by RNA polymerase II; and positive regulation of ERK1 and ERK2 cascade. Located in apical part of cell and basolateral plasma membrane. Biomarker of Alzheimer's disease; asthma; chronic obstructive pulmonary disease; rhinitis; and severe acute respiratory syndrome. [provided by Alliance of Genome Resources, Mar 2025]

complement component 4 binding protein, alpha

This gene encodes a member of a superfamily of proteins composed predominantly of tandemly arrayed short consensus repeats of approximately 60 amino acids. Along with a single, unique beta-chain, seven identical alpha-chains encoded by this gene assemble into the predominant isoform of C4b-binding protein, a multimeric protein that controls activation of the complement cascade through the classical pathway. The genes encoding both alpha and beta chains are located adjacent to each other on human chromosome 1 in the regulator of complement activation gene cluster. Two pseudogenes of this gene are also found in the cluster. [provided by RefSeq, Jul 2008]

complement component 4 binding protein, beta

This gene encodes a member of a superfamily of proteins composed predominantly of tandemly arrayed short consensus repeats of approximately 60 amino acids. A single, unique beta-chain encoded by this gene assembles with seven identical alpha-chains into the predominant isoform of C4b-binding protein, a multimeric protein that controls activation of the complement cascade through the classical pathway. C4b-binding protein has a regulatory role in the coagulation system also, mediated through the beta-chain binding of protein S, a vitamin K-dependent protein that serves as a cofactor of activated protein C. The genes encoding both alpha and beta chains are located adjacent to each other on human chromosome 1 in the regulator of complement activation gene cluster. Alternative splicing gives rise to multiple transcript variants. [provided by RefSeq, Jul 2008]

complement component 3 precursor pseudogene

Predicted to enable endopeptidase inhibitor activity. Predicted to be located in extracellular space. [provided by Alliance of Genome Resources, Mar 2025]

complement component 1, s subcomponent

This gene encodes a serine protease, which is a major constituent of the human complement subcomponent C1. C1s associates with two other complement components C1r and C1q in order to yield the first component of the serum complement system. Defects in this gene are the cause of selective C1s deficiency. [provided by RefSeq, Mar 2009]

complement component 1, r subcomponent

This gene encodes a member of the peptidase S1 protein family. The encoded protein is a proteolytic subunit in the complement system C1 complex. The complement system acts as a mediator in the innate immune response by ultimately triggering phagocytosis, inflammation, and rupturing the bacterial cell wall. Mutations in this gene are associated with Ehlers-Danlos Syndrome. [provided by RefSeq, Dec 2018]

complement factor H-related protein 3-like

complement component (3d/Epstein Barr virus) receptor 2

This gene encodes a membrane protein, which functions as a receptor for Epstein-Barr virus (EBV) binding on B and T lymphocytes. Genetic variations in this gene are associated with susceptibility to systemic lupus erythematosus type 9 (SLEB9). Alternatively spliced transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, Sep 2009]

complement component (3b/4b) receptor 1 (Knops blood group)

This gene is a member of the receptors of complement activation (RCA) family and is located in the 'cluster RCA' region of chromosome 1. The genome is polymorphic at this locus with allele-specific splice variants encoding different isoforms, based on the presence/absence of long homologous repeats (LHRs). The gene encodes a monomeric single-pass type I membrane glycoprotein found on erythrocytes, leukocytes, glomerular podocytes, and splenic follicular dendritic cells. The Knops blood group system is a system of antigens located on this protein. The protein mediates cellular binding to particles and immune complexes that have activated complement. Decreases in expression of this protein and/or mutations in this gene have been associated with gallbladder carcinomas, mesangiocapillary glomerulonephritis, systemic lupus erythematosus, sarcoidosis and Alzheimer's disease. Mutations in this gene have also been associated with a reduction in Plasmodium falciparum rosetting, conferring protection against severe malaria. [provided by RefSeq, May 2020]

complement component 1, q subcomponent, B chain

This gene encodes the B-chain polypeptide of serum complement subcomponent C1q, which associates with C1r and C1s to yield the first component of the serum complement system. C1q is composed of 18 polypeptide chains which include 6 A-chains, 6 B-chains, and 6 C-chains. Each chain contains an N-terminal collagen-like region and a C-terminal C1q globular domain. C1q deficiency is associated with lupus erythematosus and glomerulonephritis. [provided by RefSeq, Dec 2016]

complement component 7 pseudogene

complement component (3b/4b) receptor 1 (Knops blood group) pseudogene

complement component 4B (Chido blood group), copy 2

This gene encodes the basic form of complement factor 4, part of the classical activation pathway. The protein is expressed as a single chain precursor which is proteolytically cleaved into a trimer of alpha, beta, and gamma chains prior to secretion. The trimer provides a surface for interaction between the antigen-antibody complex and other complement components. The alpha chain may be cleaved to release C4 anaphylatoxin, a mediator of local inflammation. Deficiency of this protein is associated with systemic lupus erythematosus. This gene localizes to the major histocompatibility complex (MHC) class III region on chromosome 6. Varying haplotypes of this gene cluster exist, such that individuals may have 1, 2, or 3 copies of this gene. In addition, this gene exists as a long form and a short form due to the presence or absence of a 6.4 kb endogenous HERV-K retrovirus in intron 9. This GeneID and its associated RefSeq record represent a second copy of C4B found on ALT_REF_LOCI_7. [provided by RefSeq, Jul 2011]

complement component 4A (Rodgers blood group)

This gene encodes the acidic form of complement factor 4, part of the classical activation pathway. The protein is expressed as a single chain precursor which is proteolytically cleaved into a trimer of alpha, beta, and gamma chains prior to secretion. The trimer provides a surface for interaction between the antigen-antibody complex and other complement components. The alpha chain is cleaved to release C4 anaphylatoxin, an antimicrobial peptide and a mediator of local inflammation. Deficiency of this protein is associated with systemic lupus erythematosus and type I diabetes mellitus. This gene localizes to the major histocompatibility complex (MHC) class III region on chromosome 6. Varying haplotypes of this gene cluster exist, such that individuals may have 1, 2, or 3 copies of this gene. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Nov 2014]

complement component 4 binding protein, alpha pseudogene 1

complement factor H-related 2

This gene belongs to a family of complement factor H-related genes (CFHR), which are clustered together with complement factor H gene on chromosome 1, and are involved in regulation of complement. Mutations in CFHR genes have been associated with dense deposit disease and atypical haemolytic-uraemic syndrome. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Aug 2015]

complement factor H-related 3

The protein encoded by this gene is a secreted protein, which belongs to the complement factor H-related protein family. It binds to heparin, and may be involved in complement regulation. Mutations in this gene are associated with decreased risk of age-related macular degeneration, and with an increased risk of atypical hemolytic-uremic syndrome. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Oct 2011]

complement factor H-related 1

This gene encodes a secreted protein belonging to the complement factor H protein family. It binds to Pseudomonas aeruginosa elongation factor Tuf together with plasminogen, which is proteolytically activated. It is proposed that Tuf acts as a virulence factor by acquiring host proteins to the pathogen surface, controlling complement, and facilitating tissue invasion. Mutations in this gene are associated with an increased risk of atypical hemolytic-uremic syndrome. [provided by RefSeq, Oct 2009]

complement factor H-related 4

This gene is a member of the complement factor H (CFH) gene family, and encodes one of the 5 CFH-related (CFHR) proteins. These 5 genes are closely linked to the CFH gene on chromosome 1q31-q32. The CFHRs are secreted plasma proteins synthesized primarily by the hepatocytes, and composed of highly-related short consensus repeats (SCRs). This protein enhances the cofactor activity of CFH, and is involved in complement regulation. It can associate with lipoproteins and may play a role in lipid metabolism. Alternatively spliced transcript variants encoding different isoforms (varying in the number of SCRs) have been described for this gene. [provided by RefSeq, Jan 2011]

complement factor H-related 5

This gene is a member of a small complement factor H (CFH) gene cluster on chromosome 1. Each member of this gene family contains multiple short consensus repeats (SCRs) typical of regulators of complement activation. The protein encoded by this gene has nine SCRs with the first two repeats having heparin binding properties, a region within repeats 5-7 having heparin binding and C reactive protein binding properties, and the C-terminal repeats being similar to a complement component 3 b (C3b) binding domain. This protein co-localizes with C3, binds C3b in a dose-dependent manner, and is recruited to tissues damaged by C-reactive protein. Allelic variations in this gene have been associated, but not causally linked, with two different forms of kidney disease: membranoproliferative glomerulonephritis type II (MPGNII) and hemolytic uraemic syndrome (HUS). [provided by RefSeq, Jan 2010]

complement C3-like

CD46 molecule, complement regulatory protein

The protein encoded by this gene is a type I membrane protein and is a regulatory part of the complement system. The encoded protein has cofactor activity for inactivation of complement components C3b and C4b by serum factor I, which protects the host cell from damage by complement. In addition, the encoded protein can act as a receptor for the Edmonston strain of measles virus, human herpesvirus-6, and type IV pili of pathogenic Neisseria. Finally, the protein encoded by this gene may be involved in the fusion of the spermatozoa with the oocyte during fertilization. Mutations at this locus have been associated with susceptibility to hemolytic uremic syndrome. Alternatively spliced transcript variants encoding different isoforms have been described. [provided by RefSeq, Jun 2010]

complement component 1, q subcomponent-like 1

Predicted to enable signaling receptor binding activity. Predicted to be involved in locomotory behavior. Predicted to act upstream of or within maintenance of synapse structure; motor learning; and neuron remodeling. Predicted to be located in several cellular components, including climbing fiber; extracellular region; and presynapse. Predicted to be part of collagen trimer. Predicted to be active in cerebellar climbing fiber to Purkinje cell synapse and synaptic cleft. [provided by Alliance of Genome Resources, Mar 2025]

complement component 1, q subcomponent-like 2

Predicted to enable identical protein binding activity. Predicted to be involved in neurotransmitter receptor localization to postsynaptic specialization membrane; postsynaptic density assembly; and regulation of synapse maturation. Predicted to be located in extracellular region. Predicted to be part of collagen trimer. Predicted to be active in cerebellar climbing fiber to Purkinje cell synapse; hippocampal mossy fiber to CA3 synapse; and synaptic cleft. [provided by Alliance of Genome Resources, Mar 2025]

complement component 1, q subcomponent-like 3

Predicted to enable identical protein binding activity. Predicted to be involved in neurotransmitter receptor localization to postsynaptic specialization membrane and postsynaptic density assembly. Predicted to act upstream of or within regulation of synapse organization. Predicted to be located in extracellular region. Predicted to be part of collagen trimer. Predicted to be active in glutamatergic synapse; hippocampal mossy fiber to CA3 synapse; and synaptic cleft. [provided by Alliance of Genome Resources, Mar 2025]

complement component 1, q subcomponent-like 4

Predicted to enable identical protein binding activity. Predicted to act upstream of or within negative regulation of ERK1 and ERK2 cascade; negative regulation of fat cell differentiation; and negative regulation of fibroblast proliferation. Predicted to be located in extracellular space. Predicted to be part of collagen trimer. [provided by Alliance of Genome Resources, Mar 2025]

complement component 9

This gene encodes the final component of the complement system. It participates in the formation of the Membrane Attack Complex (MAC). The MAC assembles on bacterial membranes to form a pore, permitting disruption of bacterial membrane organization. Mutations in this gene cause component C9 deficiency. [provided by RefSeq, Feb 2009]

complement component 3

Complement component C3 plays a central role in the activation of complement system. Its activation is required for both classical and alternative complement activation pathways. The encoded preproprotein is proteolytically processed to generate alpha and beta subunits that form the mature protein, which is then further processed to generate numerous peptide products. The C3a peptide, also known as the C3a anaphylatoxin, modulates inflammation and possesses antimicrobial activity. Mutations in this gene are associated with atypical hemolytic uremic syndrome and age-related macular degeneration in human patients. [provided by RefSeq, Nov 2015]

complement component 2

Component C2 is a serum glycoprotein that functions as part of the classical pathway of the complement system. Activated C1 cleaves C2 into C2a and C2b. The serine proteinase C2a then combines with complement factor 4b to create the C3 or C5 convertase. Deficiency of C2 has been reported to associated with certain autoimmune diseases and SNPs in this gene have been associated with altered susceptibility to age-related macular degeneration. This gene localizes within the class III region of the MHC on the short arm of chromosome 6. Alternative splicing results in multiple transcript variants encoding distinct isoforms. Additional transcript variants have been described in publications but their full-length sequence has not been determined.[provided by RefSeq, Mar 2009]

complement component 7

This gene encodes a serum glycoprotein that forms a membrane attack complex together with complement components C5b, C6, C8, and C9 as part of the terminal complement pathway of the innate immune system. The protein encoded by this gene contains a cholesterol-dependent cytolysin/membrane attack complex/perforin-like (CDC/MACPF) domain and belongs to a large family of structurally related molecules that form pores involved in host immunity and bacterial pathogenesis. This protein initiates membrane attack complex formation by binding the C5b-C6 subcomplex and inserts into the phospholipid bilayer, serving as a membrane anchor. Mutations in this gene are associated with a rare disorder called C7 deficiency. [provided by RefSeq, Nov 2016]

complement component 6

This gene encodes a component of the complement cascade. The encoded protein is part of the membrane attack complex that can be incorporated into the cell membrane and cause cell lysis. Mutations in this gene are associated with complement component-6 deficiency. Transcript variants encoding the same protein have been described.[provided by RefSeq, Nov 2012]

complement component 5

This gene encodes a component of the complement system, a part of the innate immune system that plays an important role in inflammation, host homeostasis, and host defense against pathogens. The encoded preproprotein is proteolytically processed to generate multiple protein products, including the C5 alpha chain, C5 beta chain, C5a anaphylatoxin and C5b. The C5 protein is comprised of the C5 alpha and beta chains, which are linked by a disulfide bridge. Cleavage of the alpha chain by a convertase enzyme results in the formation of the C5a anaphylatoxin, which possesses potent spasmogenic and chemotactic activity, and the C5b macromolecular cleavage product, a subunit of the membrane attack complex (MAC). Mutations in this gene cause complement component 5 deficiency, a disease characterized by recurrent bacterial infections. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Nov 2015]

complement component 1, q subcomponent, C chain

This gene encodes the C-chain polypeptide of serum complement subcomponent C1q, which associates with C1r and C1s to yield the first component of the serum complement system. C1q is composed of 18 polypeptide chains which include 6 A-chains, 6 B-chains, and 6 C-chains. Each chain contains an N-terminal collagen-like region and a C-terminal C1q globular domain. C1q deficiency is associated with lupus erythematosus and glomerulonephritis. [provided by RefSeq, Dec 2016]

complement component 1, q subcomponent, A chain

This gene encodes the A-chain polypeptide of serum complement subcomponent C1q, which associates with C1r and C1s to yield the first component of the serum complement system. C1q deficiency is associated with lupus erythematosus and glomerulonephritis. C1q is composed of 18 polypeptide chains which include 6 A-chains, 6 B-chains, and 6 C-chains. Each chain contains an N-terminal collagen-like region and a C-terminal C1q globular domain. Alternate splicing results in multiple transcript variants. [provided by RefSeq, Nov 2016]

complement component 3a receptor 1

C3a is an anaphylatoxin released during activation of the complement system. The protein encoded by this gene is an orphan G protein-coupled receptor for C3a. Binding of C3a by the encoded receptor activates chemotaxis, granule enzyme release, superoxide anion production, and bacterial opsonization. [provided by RefSeq, May 2016]

complement C4A (Rodgers blood group)-like