LOCATION OF CAMP-DEPENDENT PROTEIN-KINASE TYPE-I WITH THE TCR-CD3 COMPLEX

Selective activation of cyclic adenosine 3',5'-monophosphate (cAMP)-de pendent protein kinase type I (cAKI), but not type II, is sufficient t o mediate inhibition of T cell replication induced through the antigen -specific T cell receptor-CD3 (TCR-CD3) complex. Immunocytochemistry a nd immunoprecipitation studies of the molecular mechanism by which cAK I inhibits TCR-CD3-dependent T cell replication demonstrated that regu latory subunit Ialpha, along with its associated kinase activity, tran slocated to and interacted with the TCR-CD3 complex during T cell acti vation and capping. Regulatory subunit IIalpha did not. When stimulate d by cAMP, the cAKI localized to the TCR-CD3 complex may release kinas e activity that, through phosphorylation, might uncouple the TCR-CD3 c omplex from intracellular signaling systems.