Protein-tyrosine kinase p72 syk is activated by wheat germ agglutinin in platelets

Abstract

We previously reported a molecular cloning of porcine gene syk encoding non-receptor type 72-kDa protein-tyrosine kinase ( Taniguchi et al. (1991) J. Biol. Chem. 266, 15790–15796). In this study, we have demonstrated that p72 syk is expressed in porcine platelets at 0.1–0.2% of total protein and that the lectin wheat germ agglutinin induces an activation of p72 syk against both auto- and exogenous-substrate-phosphrylation in porcine platelets. The activation of p72 syk was abrogated by the coexistence of N-acetyl-D-glucosamine with wheat germ agglutinin. These data suggest that p72 syk is a candidate of responsible protein-tyrosine kinase for platelet activation and that cell surface glycoprotein is involved in the activation of p72 syk in platelets.