2bo9
From Proteopedia
Human carboxypeptidase A4 in complex with human latexin.
Structural highlights
Function[CBPA4_HUMAN] Metalloprotease that could be involved in the histone hyperacetylation pathway.[1] [LXN_HUMAN] Hardly reversible, non-competitive, and potent inhibitor of CPA1, CPA2 and CPA4. May play a role in inflammation.[2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe only endogenous protein inhibitor known for metallocarboxypeptidases (MCPs) is latexin, a 25-kDa protein discovered in the rat brain. Latexin, alias endogenous carboxypeptidase inhibitor, inhibits human CPA4 (hCPA4), whose expression is induced in prostate cancer cells after treatment with histone deacetylase inhibitors. hCPA4 is a member of the A/B subfamily of MCPs and displays the characteristic alpha/beta-hydrolase fold. Human latexin consists of two topologically equivalent subdomains, reminiscent of cystatins, consisting of an alpha-helix enveloped by a curved beta-sheet. These subdomains are packed against each other through the helices and linked by a connecting segment encompassing a third alpha-helix. The enzyme is bound at the interface of these subdomains. The complex occludes a large contact surface but makes rather few contacts, despite a nanomolar inhibition constant. This low specificity explains the flexibility of latexin in inhibiting all vertebrate A/B MCPs tested, even across species barriers. In contrast, modeling studies reveal why the N/E subfamily of MCPs and invertebrate A/B MCPs are not inhibited. Major differences in the loop segments shaping the border of the funnel-like access to the protease active site impede complex formation with latexin. Several sequences ascribable to diverse tissues and organs have been identified in vertebrate genomes as being highly similar to latexin. They are proposed to constitute the latexin family of potential inhibitors. Because they are ubiquitous, latexins could represent for vertebrate A/B MCPs the counterparts of tissue inhibitors of metalloproteases for matrix metalloproteinases. Structure of human carboxypeptidase A4 with its endogenous protein inhibitor, latexin.,Pallares I, Bonet R, Garcia-Castellanos R, Ventura S, Aviles FX, Vendrell J, Gomis-Ruth FX Proc Natl Acad Sci U S A. 2005 Mar 15;102(11):3978-83. Epub 2005 Feb 28. PMID:15738388[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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