Are prohormones converted to hormones during secretion?
A number of lines of evidence suggest that the polypeptide prohormone converting enzyme is a trypsin-like serine protease. A model is proposed in which the converting enzyme is activated from an inactive zymogen during secretion. Converting enzyme then activates co-secreted prohormone proteolytically. An important feature of the model lies in the geometry of the secretory granule immediately after exocytosis. It is suggested that initially diffusion of the granule contents is limited enough to allow extensive proteolysis to occur. Conversion of prohormone to hormone is terminated by diffusion of converting enzyme and prohormone from the site of release.
D000818:Animals; D003594:Cytoplasmic Granules / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism; D006728:Hormones / Q000096:biosynthesis* / Q000378:metabolism; D008954:Models, Biological; D011498:Protein Precursors / Q000378:metabolism*; D012697:Serine Endopeptidases
D006728:Hormones; D011498:Protein Precursors; D010450:Endopeptidases; D012697:Serine Endopeptidases