Platelet talin is phosphorylated by calyculin A.
Calyculin A and okadaic acid, potent and cell permeable inhibitors of type 1 and type 2A protein phosphatases, inhibit platelet aggregation and secretion. However, the relationship between phosphatase inhibition and inhibition of platelet function is not well understood. We found that in unstimulated platelets, talin (P235) was phosphorylated at threonine residues by calyculin A. Furthermore, the extent of talin phosphorylation by calyculin A was closely correlated with its inhibition of thrombin-induced platelet aggregation. Since the binding of talin to platelet glycoprotein IIb/IIIa complex has been shown to be affected by its phosphorylation, these results suggest that type 1 and/or type 2A protein phosphatases may play a role in the regulation of membrane-cytoskeleton interaction through dephosphorylation of talin.
Murata
K
K
Department of Surgery II, Osaka University Medical School, Japan.
Sakon
M
M
Kambayashi
J
J
Okuyama
M
M
Hase
T
T
Mori
T
T
D000468:Alkalies / Q000737:chemistry; D000911:Antibodies, Monoclonal; D001792:Blood Platelets / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D006801:Humans; D007553:Isotope Labeling; D008387:Marine Toxins; D010080:Oxazoles / Q000378:metabolism / Q000494:pharmacology*; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D011233:Precipitin Tests; D012694:Serine / Q000737:chemistry; D016608:Talin / Q000378:metabolism*; D013912:Threonine / Q000737:chemistry; D014443:Tyrosine / Q000737:chemistry
D000468:Alkalies; D000911:Antibodies, Monoclonal; D008387:Marine Toxins; D010080:Oxazoles; D010455:Peptides; D010761:Phosphorus Radioisotopes; D016608:Talin; D013912:Threonine; D014443:Tyrosine; D012694:Serine; C059041:calyculin A; D010749:Phosphoprotein Phosphatases