Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.9 (enterokinase)
 675 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Corin is a cardiac transmembrane serine protease. In cell-based studies, corin converted pro-atrial natriuretic peptide (pro-ANP) to mature ANP, suggesting that corin is potentially the pro-ANP convertase. In this study, we evaluated the importance of the transmembrane domain and activation cleavage in human corin. We showed that a soluble corin that consists of only the extracellular domain was capable of processing recombinant human pro-ANP in cell-based assays. In contrast, a mutation at the conserved activation cleavage site, R801A, abolished the function of corin, demonstrating that the activation cleavage is essential for corin activity. These results allowed us to design, express, and purify a mutant soluble corin, EKsolCorin, that contains an enterokinase recognition sequence at the activation cleavage site. Purified EKsolCorin was activated by enterokinase in a dose-dependent manner. Activated EK-solCorin had hydrolytic activity toward peptide substrates with a preference for Arg and Lys residues in the P-1 position. This activity of EKsolCorin was inhibited by trypsin-like serine protease inhibitors but not inhibitors of chymotrypsin-like, cysteine-, or metallo-proteases. In pro-ANP processing assays, purified active EKsolCorin converted recombinant human pro-ANP to biologically active ANP in a highly sequence-specific manner. The pro-ANP processing activity of EKsolCorin was not inhibited by human plasma. Together, our data indicate that the transmembrane domain is not necessary for the biological activity of corin but may be a mechanism to localize corin at specific sites, whereas the proteolytic cleavage at the activation site is an essential step in controlling the activity of corin.
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PMID:Functional analysis of the transmembrane domain and activation cleavage of human corin: design and characterization of a soluble corin. 1455 95

Corin is a type II transmembrane serine protease and functions as the proatrial natriuretic peptide (pro-ANP) convertase in the heart. In the extracellular region of corin, there are two frizzled-like cysteine-rich domains, eight low density lipoprotein receptor (LDLR) repeats, a macrophage scavenger receptor-like domain, and a trypsin-like protease domain at the C terminus. To examine the functional importance of the domain structures in the propeptide of corin for pro-ANP processing, we constructed a soluble corin, EKshortCorin, that consists of only the protease domain and contains an enterokinase (EK) recognition sequence at the conserved activation cleavage site. After being activated by EK, EKshortCorin exhibited catalytic activity toward chromogenic substrates but failed to cleave pro-ANP, indicating that certain domain structures in the propeptide are required for pro-ANP processing. We then constructed a series of corin deletion mutants and studied their functions in pro-ANP processing. Compared with that of the full-length corin, a corin mutant lacking frizzled 1 domain exhibited approximately 40% activity, whereas corin mutants lacking single LDLR repeat 1, 2, 3, or 4 had approximately 49, approximately 12, approximately 53, and approximately 77% activity, respectively. We also made corin mutants with a single mutation at a conserved Asp residue that coordinates Ca(2+)-binding in LDLR repeats 1, 2, 3, or 4 (D300Y, D336Y, D373Y, and D410Y) and showed that these mutants had approximately 25, approximately 11, approximately 16, and approximately 82% pro-ANP processing activity, respectively. Our results indicate that frizzled 1 domain and LDLR repeats 1-4 are important structural elements for corin to recognize its physiological substrate, pro-ANP.
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PMID:Identification of domain structures in the propeptide of corin essential for the processing of proatrial natriuretic peptide. 1519 93