Characterization of PC2, a mammalian Kex2 homologue, following expression of the cDNA in microinjected Xenopus oocytes.
A human insulinoma cDNA (PC2) that encodes a protein homologous to the Kex2/subtilisin-like proteinases has recently been described [1990, J. Biol. Chem. 265, 2997-3000]. In order to characterise the associated proteinase activity, mRNA encoding PC2 was synthesised in vitro and microinjected into Xenopus oocytes. The proteinase activity released into the media from oocytes microinjected with PC2 mRNA was assayed using small peptide fluorogenic substrates. Boc.Gln.Arg.Arg aminomethyl coumarin was hydrolysed in a Ca(2+)-dependent manner, but substrate analogues bearing a single basic aminoacid were not. The substrate specificity, inhibitor profile, and pH optimum of 5.5 were compatible with an involvement of PC2 in prohormone processing in mammalian cells.
Shennan
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Department of Medicine, University of Birmingham, Queen Elizabeth Hospital, UK.
Smeekens
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Steiner
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Docherty
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D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004247:DNA / Q000235:genetics*; D004789:Enzyme Activation / Q000187:drug effects; D015870:Gene Expression; D006801:Humans; D007340:Insulinoma; D008845:Microinjections; D009865:Oocytes / Q000378:metabolism*; D010190:Pancreatic Neoplasms; D045706:Proprotein Convertase 2; D043484:Proprotein Convertases; D011498:Protein Precursors / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases / Q000235:genetics*; D015842:Serine Proteinase Inhibitors; D013379:Substrate Specificity; D013381:Subtilisins; D014162:Transfection; D014982:Xenopus laevis
D011498:Protein Precursors; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D015842:Serine Proteinase Inhibitors; D004247:DNA; D043484:Proprotein Convertases; D012697:Serine Endopeptidases; D013381:Subtilisins; C058751:KEX2 protein, S cerevisiae; D045706:Proprotein Convertase 2; D002118:Calcium