{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nAlthough none of the provided abstracts specifically refer to a protein named “NOP9,” the collection of studies highlights key roles of several lysosomal integral membrane proteins in maintaining cellular homeostasis—and one candidate, previously known as NCU‐G1 (also referred to as GLMP), may be of related interest. For example, one study using Drosophila describes how mutations in a gene related to lysosomal functions (the spin gene) lead to neurodegeneration, behavioral defects, and reduced cell viability, underlining the importance of lysosomal integrity in cellular and organismal health."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nOther studies focus on lysosomal transporters that maintain membrane lipid balance and overall lysosomal function. In these reports the major facilitator superfamily member SPNS1 is identified as a proton‐dependent transporter that exports lysophospholipids such as lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE) from the lysosome into the cytosol. In parallel, another lysosomal transporter MFSD1 (which requires the accessory subunit GLMP for its stability) is shown to be essential for protecting lysosomal proteins from proteolytic degradation. The work on these transporters further revealed that deficiencies in these proteins lead to cellular metabolic dysregulation, impaired autophagy, and liver dysfunction."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "2", "end_ref": "6"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nNotably, several studies converge on insights regarding the lysosomal protein originally described as a nuclear factor but later reclassified as the kidney‐predominant protein NCU‐G1—a highly conserved, heavily glycosylated type I transmembrane protein endowed with a tyrosine‐based lysosomal sorting motif. Its proper lysosomal localization is critical, as demonstrated by experiments showing that mutation of its sorting motif disrupts localization. In mouse models, loss of NCU‐G1 leads to spontaneous chronic liver injury characterized by oxidative stress, cell death, fibrosis, and metabolic alterations including increased lipogenesis and altered fatty acid uptake—findings that underscore its central role in lysosomal recycling and cellular metabolic regulation."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "7", "end_ref": "10"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Y Nakano, K Fujitani, J Kurihara, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Mutations in the novel membrane protein spinster interfere with programmed cell death and cause neural degeneration in Drosophila melanogaster."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Mol Cell Biol (2001)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1128/MCB.21.11.3775-3788.2001"}], "href": "https://doi.org/10.1128/MCB.21.11.3775-3788.2001"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "11340170"}], "href": "https://pubmed.ncbi.nlm.nih.gov/11340170"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Menglan He, Alvin C Y Kuk, Mei Ding, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Spns1 is a lysophospholipid transporter mediating lysosomal phospholipid salvage."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Proc Natl Acad Sci U S A (2022)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1073/pnas.2210353119"}], "href": "https://doi.org/10.1073/pnas.2210353119"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "36161949"}], "href": "https://pubmed.ncbi.nlm.nih.gov/36161949"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "David Massa López, Melanie Thelen, Felix Stahl, et al. "}, {"type": "b", "children": [{"type": "t", "text": "The lysosomal transporter MFSD1 is essential for liver homeostasis and critically depends on its accessory subunit GLMP."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Elife (2019)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.7554/eLife.50025"}], "href": "https://doi.org/10.7554/eLife.50025"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "31661432"}], "href": "https://pubmed.ncbi.nlm.nih.gov/31661432"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "Hiroko Yanagisawa, Tomohiro Ishii, Kentaro Endo, et al. "}, {"type": "b", "children": [{"type": "t", "text": "L-leucine and SPNS1 coordinately ameliorate dysfunction of autophagy in mouse and human Niemann-Pick type C disease."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Sci Rep (2017)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1038/s41598-017-15305-9"}], "href": "https://doi.org/10.1038/s41598-017-15305-9"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "29162837"}], "href": "https://pubmed.ncbi.nlm.nih.gov/29162837"}]}, {"type": "r", "ref": 5, "children": [{"type": "t", "text": "David Massa López, Lea Kählau, Katharina Esther Julia Jungnickel, et al. 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