PKC-theta selectively controls the adhesion-stimulating molecule Rap1.

The antigen-specific interaction of a T cell with an antigen-presenting cell (APC) results in the formation of an immunologic synapse (IS) between the membranes of the 2 cells. beta(2) integrins on the T cell, namely, leukocyte function-associated antigen 1 (LFA-1) and its counter ligand, namely, immunoglobulin-like cell adhesion molecule 1 (ICAM-1) on the APC, critically stabilize this intercellular interaction. The small GTPase Rap1 controls T-cell adhesion through modulating the affinity and/or spatial organization of LFA-1; however, the upstream regulatory components triggered by the T-cell receptor (TCR) have not been resolved.