{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n HemK1 is a member of an evolutionarily conserved family of S‐adenosyl–L–methionine–dependent methyltransferases that plays a critical role in maintaining translational fidelity. In prokaryotes, HemK1 catalyzes the N⁵–glutamine methylation of the universally conserved GGQ motif in class I release factors, thereby promoting efficient translation termination and reducing read–through errors ["}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "4"}]}, {"type": "t", "text": "]. Structural and biophysical studies have revealed that HemK1 possesses a dual–domain architecture that not only coordinates substrate binding and catalysis, but also undergoes cotranslational folding—features that are essential for its proper function ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": "]. In mammalian cells, alternatively spliced variants such as mHemk1 are highly expressed in undifferentiated embryonic stem cells and have been linked to cell proliferation, while upregulation of HEMK1 in allergen–specific T cells suggests a role in modulating immune responses ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "7"}]}, {"type": "t", "text": "]. Moreover, studies in pathogenic bacteria have implicated HemK1 orthologs in the regulation of virulence pathways (for instance, modulating type III secretion systems), thereby extending its importance beyond translation termination to broader aspects of cellular regulation and host–pathogen interactions ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "9"}]}, {"type": "t", "text": "]. Collectively, these insights establish HemK1 as a multifaceted enzyme that safeguards protein synthesis, influences cellular differentiation, and may participate in immunomodulatory and pathogenic processes.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Heidi L Schubert, John D Phillips, Christopher P Hill "}, {"type": "b", "children": [{"type": "t", "text": "Structures along the catalytic pathway of PrmC/HemK, an N5-glutamine AdoMet-dependent methyltransferase."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Biochemistry (2003)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1021/bi034026p"}], "href": "https://doi.org/10.1021/bi034026p"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "12741815"}], "href": "https://pubmed.ncbi.nlm.nih.gov/12741815"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Zhe Yang, Lance Shipman, Meng Zhang, et al. 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