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PAM: diverse roles in neuroendocrine cells, cardiomyocytes, and green algae
Author(s) -
Bäck Nils,
Mains Richard E.,
Eipper Betty A.
Publication year - 2022
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.16049
Subject(s) - chlamydomonas reinhardtii , secretory vesicle , secretion , biology , enteroendocrine cell , biochemistry , microbiology and biotechnology , secretory pathway , enzyme , cell , gene , exocytosis , golgi apparatus , hormone , endocrine system , mutant
Our understanding of the ways in which peptides are used for communication in the nervous and endocrine systems began with the identification of oxytocin, vasopressin, and insulin, each of which is stored in electron‐dense granules, ready for release in response to an appropriate stimulus. For each of these peptides, entry of its newly synthesized precursor into the ER lumen is followed by transport through the secretory pathway, exposing the precursor to a sequence of environments and enzymes that produce the bioactive products stored in mature granules. A final step in the biosynthesis of many peptides is C‐terminal amidation by peptidylglycine α‐amidating monooxygenase (PAM), an ascorbate‐ and copper‐dependent membrane enzyme that enters secretory granules along with its soluble substrates. Biochemical and cell biological studies elucidated the highly conserved mechanism for amidated peptide production and raised many questions about PAM trafficking and the effects of PAM on cytoskeletal organization and gene expression. Phylogenetic studies and the discovery of active PAM in the ciliary membranes of Chlamydomonas reinhardtii , a green alga lacking secretory granules, suggested that a PAM‐like enzyme was present in the last eukaryotic common ancestor. While the catalytic features of human and C. reinhardtii PAM are strikingly similar, the trafficking of PAM in C. reinhardtii and neuroendocrine cells and secretion of its amidated products differ. A comparison of PAM function in neuroendocrine cells, atrial myocytes, and C. reinhardtii reveals multiple ways in which altered trafficking allows PAM to accomplish different tasks in different species and cell types.

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