Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.17 (PCE)
 1,301 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent reports reveal that the C-terminal half of the neuroendocrine polypeptide 7B2 selectively inhibits and binds PC2, a mammalian prohormone converting enzyme that is homologous to the yeast pro-alpha-factor processing protease Kex2. During attempted secretion of the 185 amino-acid human 7B2 in Saccharomyces cerevisiae, we observe that the protein is mostly retained inside the cell. However a mutant polypeptide (7B2 delta 1), where the C-terminal 48 amino acids of 7B2 are deleted, is efficiently secreted. Two shorter C-terminal truncations either permit poor secretion or no secretion at all. Surprisingly, full-length 7B2 but not 7B2 delta 1 abolishes the catalytic activity of Kex2, indicating that C-terminal residues of 7B2 might also be important for inhibition of the yeast protease. When the KEX2 gene is disrupted, yeast cells unexpectedly secrete a 7B2 variant similar in size to 7B2 delta 1, suggesting involvement of the alternate yeast prohormone convertase Yap3 in processing. Secretion is enhanced by overexpression of Yap3 and by the presence of a Lys-Arg residue at the processing site of precursor 7B2. These results purport that, in neuroendocrine cells too, secretion of 7B2 could be mediated by a homologue of Yap3.
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PMID:A C-terminal domain, which prevents secretion of the neuroendocrine protein 7B2 in Saccharomyces cerevisiae, inhibits Kex2 yet is processed by the Yap3 protease. 775 May 51

'Prohormone thiol protease' (PTP) represents the major enkephalin precursor processing activity in chromaffin granules. In this study, cleavage specificity of PTP for paired basic and monobasic residues was examined with a series of model peptide-MCA (-methylcoumarinamide) substrates. Monobasic peptides were cleaved at the COOH- and NH2-terminal sides of the single basic residue. Dibasic peptides, however, were preferentially cleaved at the NH2-terminal side of the pair, or between the two basic residues, with low cleavage at the COOH-terminal side of the pair. Inhibition by the peptide inhibitor (D-Tyr)-Glu-Phe-Lys-Arg-CH2Cl provided further evidence for PTP's specificity for the dibasic Lys-Arg site. Inhibition by Z-Leu-Val-Gly-CHN2 and Z-Arg-Leu-Val-Gly-CHN2 suggests involvement of Val-Gly in substrate binding to PTP; these two cystatin C-related inhibitors also indicate PTP as a cysteine protease. These results demonstrate PTP's unique cleavage specificity that differs from other processing endopeptidases, including the subtilisin-related proprotein convertases, PC1/PC3, and PC2, as well as the pituitary proopiomelanocortin-converting enzyme, PCE. This study provides further evidence for PTP as a novel prohormone processing enzyme that belongs to the class of cysteine proteases.
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PMID:Unique cleavage specificity of 'prohormone thiol protease' related to proenkephalin processing. 813 39

The mouse neuroblastoma cell line (Neuro 2 A) has been shown to contain the mRNA of a prohormone converting enzyme, PC2. The Chinese hamster ovary cell line (CHO) does not express PC2 mRNA, but is thought to contain the ubiquitous protease, furin. The enzyme(s) responsible for releasing corticotrophin-releasing hormone (CRH) from its precursor (proCRH) have not been identified, therefore to investigate the possible function(s) of PC2 or furin in the processing of proCRH, stable Neuro 2 A and CHO cell lines that express the 21 kDa human (h)proCRH were established. A specific two-site IRMA for CRH demonstrated that the hpreproCRH-expressing Neuro 2 A cell line cleaved the CRH precursor to the CRH peptide, and was able to release the mature peptide into cell medium at levels that were 4-fold higher than produced by the hproCRH-expressing CHO cells. RIA showed that the CHO cells secreted levels of CRH-containing peptides that were 10-fold higher than produced by the Neuro 2 A cells. Medium from the transfected CHO and Neuro 2 A cells was analysed by HPLC; this showed that CHO cells released a single protein corresponding to the unprocessed CRH precursor, whereas Neuro 2 A cells secreted two peptides, which could be identified as the 5 kDa CRH(1-41) and residual 16 kDa CRH peptides. These results suggest that Neuro 2 A cells, which contain PC2, can process proCRH to the mature peptide.
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PMID:Post-translational processing of human procorticotrophin-releasing factor in transfected mouse neuroblastoma and Chinese hamster ovary cell lines. 937 20