Membrane binding and autolytic activation of calpain-I in human platelets.
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.
Ariyoshi
H
H
Department of Surgery II, Osaka University Medical School, Japan.
Shiba
E
E
Sakon
M
M
Kambayashi
J
J
Kawasaki
T
T
Kang
J
J
Kawashima
S
S
Mori
T
T
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
D004151:Dipeptides; C071482:calpeptin; D002154:Calpain; D002118:Calcium