Direct Interaction in T-cells between θPKC and the Tyrosine Kinase p59fyn

The protein kinase C (PKC) family has been clearly implicated in T-cell activation as have several nonreceptor protein-tyrosine kinases associated with the T-cell receptor, including p59fyn. This report demonstrates that θPKC and p59fyn specifically interact in vitro , in the yeast two-hybrid system, and in T-cells. Further indications of direct interaction are that p59fyn potentiates θPKC catalytic activity and that θPKC is a substrate for tyrosine phosphorylation by p59fyn. This interaction may account for the localization of θPKC following T-cell activation, pharmacological disruption of which results in specific cell-signaling defects. The demonstration of a physical interaction between a PKC and a protein-tyrosine kinase expands the class of PKC-anchoring proteins (receptors for activated C kinases (RACKs)) and demonstrates a direct connection between these two major T-cell-signaling pathways.