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Leupeptin does not affect the normal signal transduction mechanism in platelets
Author(s) -
Alonso M.T.,
Sanchez A.,
Herreros B.
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)80573-3
Subject(s) - leupeptin , calpain , protein kinase c , thrombin , chemistry , proteases , biochemistry , phorbol , microbiology and biotechnology , signal transduction , filamin , protein kinase a , platelet , kinase , biology , enzyme , protease , cytoskeleton , immunology , cell
Calpains are Ca 2+ ‐dependent serine proteases that can regulate protein kinase C‐mediated cellular events by cleaving the membrane‐bound native enzyme to yield an activated cytosolic fragment. Inhibition of calpain by leupeptin may cause enhancement or inhibition of cellular functions depending on the nature of the protein kinase C reaction involved. We have studied the effects of leupeptin on platelet responses (aggregation, secretion, thromboxane B 2 formation and intracellular Ca 2+ and pH changes) induced by either thrombin, collagen or phorbol 12‐myristate 13‐acetate (TPA), which are known to activate protein kinase C by different mechanisms. Only thrombin‐induced responses were inhibited by leupeptin. This suggests that the inhibitory effect of leupeptin is not due to antagonism of calpain in this system, but to direct interference with the proteolytic effect of thrombin.