A basic 18-amino acid peptide contains the polysulfate-binding domain responsible for activation of the boar proacrosin/acrosin system.
Proacrosin is the zymogen of acrosin, a serine protease localized in the acrosomal matrix of mammalian sperm. Proacrosin/acrosin binds to solubilized zona pellucida glycoproteins (ZPGs) and various polysulfates in a non-enzymatic mechanism. In addition, both polysulfates and ZPGs induce proacrosin activation once they bind to the polysulfate-binding domain (PSBD) of the enzyme. We show here that the peptide (43)IFMYHNNRRYHTCGGILL(60) inhibited the proacrosin activation induced by either fucoidan or ZPGs. In addition, the peptide was recognized by the monoclonal antibody C5F10, which is directed against the PSBD region. Our data suggest that the PSBD is composed of many "subsites" that may or may not interact with each other.
Moreno
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Laboratory of Embryology, Faculty of Biological Sciences, Pontifical Catholic University of Chile, Santiago, Chile.
Barros
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D000176:Acrosin / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity; D001665:Binding Sites; D004527:Egg Proteins / Q000378:metabolism / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004792:Enzyme Precursors / Q000737:chemistry* / Q000378:metabolism*; D000939:Epitopes / Q000276:immunology; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism / Q000494:pharmacology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000494:pharmacology; D011134:Polysaccharides / Q000494:pharmacology; D011956:Receptors, Cell Surface; D013431:Sulfates / Q000378:metabolism*; D013552:Swine; D000072216:Zona Pellucida Glycoproteins
D000911:Antibodies, Monoclonal; D004527:Egg Proteins; D004792:Enzyme Precursors; D000939:Epitopes; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; D011134:Polysaccharides; D011956:Receptors, Cell Surface; D013431:Sulfates; D000072216:Zona Pellucida Glycoproteins; C007789:fucoidan; C022438:proacrosin; D000176:Acrosin