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Novel Chromaffin Granule Serpins, Endopin 1 and Endopin 2
Author(s) -
HOOK VIVIAN Y.H.,
YASOTHORNSRIKUL SUKKID,
HWANG SHINRONG
Publication year - 2002
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2002.tb04505.x
Subject(s) - proteases , chromaffin cell , serpin , protease , biochemistry , trypsin , chemistry , cathepsin , cathepsin b , cysteine protease , secretion , proteolysis , biology , microbiology and biotechnology , enzyme , adrenal medulla , endocrinology , catecholamine , gene
A bstract : Endopin 1 and endopin 2 represent two novel serpin protease inhibitors localized within chromaffin granules, secretory vesicles of adrenomedullary chromaffin cells that represent a model neuroendocrine cell for synthesis and secretion of peptide neurotransmitters. This chapter describes the molecular features of the primary sequences of endopin 1 and endopin 2 that provided prediction of their distinct target protease specificities. Endopin 1 inhibits trypsin that cleaves at basic residues. In contrast, endopin 2 possesses cross‐class inhibition of papain and elastase that represent cysteine and serine proteases, respectively. Cell biological studies indicate that endopin 1 and endopin 2 are localized within chromaffin granules. These results implicate endopin 1 inhibition in vivo of trypsin‐like proteases in secretory vesicles, and endopin 2 inhibition of papain‐ or elastase‐like proteases. Indeed, endopin 2 inhibits the endogenous cysteine protease PTP (prohormone thiol protease), present in chromaffin granules, that participates in the proteolytic processing of proenkephalin. These findings indicate the presence of endogenous endopin 1 and endopin 2 in secretory vesicle function.