A GENERAL STRATEGY FOR PRODUCING CONDITIONAL ALLELES OF SRC-LIKE TYROSINE KINASES

The Src-like tyrosine kinases require membrane localization for transf ormation and probably for their normal role in signal transduction, We utilized this characteristic to prepare Src-like tyrosine kinases tha t can be readily activated with the rationally designed chemical induc er of dimerization FK1012. Dimerization of cytoplasmic Src-like tyrosi ne kinases was not sufficient for signaling, but their recruitment to the plasma membrane led to the rapid activation of transcription facto rs identical to those regulated by crosslinking the antigen receptor. Moreover, recruitment of activated Src-like kinases to the membrane re placed signaling by the T-lymphocyte antigen receptor complex, leading to the activation of both the Ras/protein kinase C and Ca2+/calcineur in pathways normally activated by antigen receptor signaling. Since th ese chemical inducers of dimerization are cell permeable, this approac h permits the production of conditional alleles of any of the Src-like tyrosine kinases, thereby allowing a delineation of their development al roles.