Kex2-like proteolytic activity in adrenal medullary chromaffin granules.
This study demonstrates the presence of boc-Gln-Arg-Arg-MCA cleaving activity in bovine chromaffin granule membranes that resembles yeast Kex2 proteolytic activity. The chromaffin granule boc-Gln-Arg-Arg-MCA cleaving activity, like Kex2 proteolytic activity, shows calcium dependence, optimum activity at pH 7.5-8.2, inhibition by serine protease inhibitors, and preference for cleavage at the COOH-terminal side of Arg-Arg and Lys-Arg, over Lys-Lys, paired basic residues. Potent inhibition by the active-site directed inhibitor [D-Tyr]-Glu-Phe-Lys-Arg-CK (20 microM) provided further evidence for dibasic residue cleavage site specificity. These results are the first report of endogenous mammalian Kex2-like proteolytic activity that may be related to PC1/PC3 and PC2 enzymes, the newly discovered mammalian homologues of Kex2 protease. It will be important to determine the role of this Kex2-like proteolytic activity in processing the precursors of adrenal medullary neuropeptides.
Azaryan
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Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, MD 20814.
Hook
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D000313:Adrenal Medulla / Q000201:enzymology*; D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002837:Chromaffin Granules / Q000201:enzymology*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000378:metabolism; D045706:Proprotein Convertase 2; D043484:Proprotein Convertases; D011480:Protease Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051578:Proto-Oncogene Proteins c-fes; D012333:RNA, Messenger / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases / Q000187:drug effects / Q000378:metabolism*; D013381:Subtilisins
D009842:Oligopeptides; D011480:Protease Inhibitors; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D011505:Protein-Tyrosine Kinases; D051578:Proto-Oncogene Proteins c-fes; D043484:Proprotein Convertases; D012697:Serine Endopeptidases; D013381:Subtilisins; C058751:KEX2 protein, S cerevisiae; D045706:Proprotein Convertase 2