AN EPSTEIN-BARR-VIRUS TRANSFORMATION-ASSOCIATED MEMBRANE-PROTEIN INTERACTS WITH SRC FAMILY TYROSINE KINASES

In latently infected growth-transformed human lymphocytes, Epstein-Barr virus (EBV) encodes two integral plasma membrane proteins: LMP1, which constitutively induces B-lymphocyte activation and intercellular adhesion, and LMP2A, which associates with LMP1 and is a tyrosine kinase substrate. We now demonstrate that LMP2A associates with Nrc family protein tyrosine kinases, particularly lyn kinase, in nonionic detergent extracts of transfected B lymphoma cells or in extracts of EBV-transformed B lymphocytes. The LMP2A and tyrosine kinase association is stable in nonionic detergents and includes a 70-kDa cell protein which is also an in vitro or in vivo kinase substrate. This LMP2A association with B-lymphocyte src family tyrosine kinases is likely to be an important pathway in EBV's effects on cell growth.