{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nPeptidylglycine α‐amidating monooxygenase (PAM) functions as a critical cuproenzyme that catalyzes the C‐terminal amidation of peptide hormones and neuropeptides—a reaction essential for their full biological activity. Studies have shown that both common and rare coding variants in PAM can impair its expression and catalytic efficiency, leading to defects in hormone processing that are linked to metabolic disorders such as type 2 diabetes and abnormal pituitary hormone secretion. The amidation reaction itself is tightly regulated by the enzyme’s copper‐dependent active site, whose activity is exquisitely sensitive to pH, oxygen tension, and subtle rearrangements in electron transfer pathways. These mechanistic insights have been demonstrated by kinetic studies that dissect distinct electron transfer routes, and by efforts to produce recombinant catalytic domains that recapitulate the enzyme’s native kinetics."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "6"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn addition to its enzymatic role, PAM expression and subcellular localization are under tight regulatory control. Binding of regulatory proteins (such as the La autoantigen) to a specific 3′ untranslated region of PAM mRNA modulates its nuclear export and, consequently, the overall levels of PAM, thereby influencing peptide amidation. Moreover, PAM undergoes a sophisticated endocytic trafficking itinerary—it is internalized from the plasma membrane, enters the multivesicular body pathway, and is then recycled back to the trans‐Golgi network. Such dynamic trafficking likely ensures that amidation occurs in the appropriate cellular locale and that active enzyme is available for protein processing."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "7"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nBeyond its canonical amidating activity, genetic studies have implicated PAM in diverse physiological and pathological contexts. Multiple association studies have linked PAM variants not only to impaired β‐cell function and type 2 diabetes risk but also to blood pressure regulation via effects on atrial natriuretic peptide secretion, as well as to pituitary hypersecretion syndromes. Furthermore, a homolog of PAM—known in neuronal contexts as MYCBP2—is a conserved component of a noncanonical ubiquitin ligase complex that modulates axon guidance and degeneration through the regulation of target proteins such as NMNAT2. Collectively, these findings underscore the pleiotropic roles of PAM, from the biochemical catalysis of peptide amidation to broader impacts on endocrine, metabolic, and neurodevelopmental processes."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "9", "end_ref": "14"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Valgerdur Steinthorsdottir, Gudmar Thorleifsson, Patrick Sulem, et al. 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"}, {"type": "b", "children": [{"type": "t", "text": "Striking Oxygen Sensitivity of the Peptidylglycine α-Amidating Monooxygenase (PAM) in Neuroendocrine Cells."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2015)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M115.667246"}], "href": "https://doi.org/10.1074/jbc.M115.667246"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "26296884"}], "href": "https://pubmed.ncbi.nlm.nih.gov/26296884"}]}, {"type": "r", "ref": 5, "children": [{"type": "t", "text": "Shefali Chauhan, Parisa Hosseinzadeh, Yi Lu, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Stopped-Flow Studies of the Reduction of the Copper Centers Suggest a Bifurcated Electron Transfer Pathway in Peptidylglycine Monooxygenase."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Biochemistry (2016)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1021/acs.biochem.6b00061"}], "href": "https://doi.org/10.1021/acs.biochem.6b00061"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "26982589"}], "href": "https://pubmed.ncbi.nlm.nih.gov/26982589"}]}, {"type": "r", "ref": 6, "children": [{"type": "t", "text": "Sumit Handa, Tyler J Spradling, Daniel R Dempsey, et al. 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