GLYCOPROTEIN VI IS THE COLLAGEN RECEPTOR IN PLATELETS WHICH UNDERLIESTYROSINE PHOSPHORYLATION OF THE FC RECEPTOR GAMMA-CHAIN

We have recently shown that collagen activates platelets through a pat hway dependent on the Fc receptor gamma-chain and the tyrosine kinase Syk, We report here that the Fc receptor gamma-chain and the candidate collagen receptor glycoprotein VI (GPVI) co-associate, Furthermore, c ross-linking GPVI stimulates a similar pattern of tyrosine phosphoryla tion to that stimulated by collagen, including tyrosine phosphorylatio n of Fc receptor gamma-chain, These results support a model where GPVI couples collagen-stimulation of platelets to phosphorylation of the P c receptor gamma-chain leading to activation of Syk and phospholipase C gamma 2. (C) 1997 Federation of European Biochemical Societies.