title: Membrane binding and autolytic activation of calpain-I in human platelets.
abstract: The binding of calpain-I (Ca2+ activated neutral protease with high Ca2+ sensitivity) to the membranes of human platelets and the subsequent autolytic activation of calpain-I were analyzed by an immunoblot technique. In A23187 stimulated platelets, cytosolic calpain-I translocated to the membranes with autolysis in a Ca2+ dependent manner and simultaneously underwent autolysis. Although calpeptin, a cell permeable calpain inhibitor, inhibited autolysis of calpain-I, it was unable to prevent the translocation of calpain-I. In a cell re-constituted system, the membrane binding of calpain-I was also Ca2+ dependent and was significantly inhibited by a substrate of calpain. It was suggested that the binding of calpain-I to the membranes required the substrate binding site of this enzyme.
authors.affiliation: Department of Surgery II, Osaka University Medical School, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ariyoshi
authors.forename: E
authors.initials: E
authors.lastname: Shiba
authors.forename: M
authors.initials: M
authors.lastname: Sakon
authors.forename: J
authors.initials: J
authors.lastname: Kambayashi
authors.forename: T
authors.initials: T
authors.lastname: Kawasaki
authors.forename: J
authors.initials: J
authors.lastname: Kang
authors.forename: S
authors.initials: S
authors.lastname: Kawashima
authors.forename: T
authors.initials: T
authors.lastname: Mori
mesh_terms: D001692:Biological Transport / Q000502:physiology; D001792:Blood Platelets / Q000201:enzymology*; D002118:Calcium / Q000502:physiology; D002154:Calpain / Q000037:antagonists & inhibitors / Q000097:blood*; D002462:Cell Membrane / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D004151:Dipeptides / Q000494:pharmacology; D004789:Enzyme Activation; D006801:Humans; D015151:Immunoblotting; D011485:Protein Binding
chemical_list: D004151:Dipeptides; C071482:calpeptin; D002154:Calpain; D002118:Calcium