ACTIVATION OF TSK AND BTK TYROSINE KINASES BY G PROTEIN BETA-GAMMA SUBUNITS

摘要

Tsk/Itk and Btk are members of the pleckstrin-homology (PH) domain-containing tyrosine kinase family. The PH domain has been demonstrated to be able to interact with beta gamma subunits of heterotrimeric guanine nucleotide-binding proteins (G proteins) (G(beta gamma)) and phospholipids. Using cotransfection assays, we show here that the kinase activities of Tsk and Btk are stimulated by certain G(beta gamma) subunits. Furthermore, using an in vitro reconstitution assay with purified bovine brain G(beta gamma) subunits and the immunoprecipitated Tsk, we find that Tsk kinase activity is increased by G(beta gamma) subunits and another membrane factor(s). These results indicate that this family of tyrosine kinases could be an effector of heterotrimeric G proteins. [References: 41]