Fig. 7.

A model for the antiapoptotic interplay between U_S3 and PKA. Earlier studies have shown that the U_S3 protein kinase blocks apoptosis induced by d120, a replication-incompetent virus, and by ectopically expressed BAD protein. This report shows that activated PKA blocks apoptosis induced by either d120 mutant or BAD protein, and that U_S3 can phosphorylate PKA substrates including the autophosphorylation site of the RIIα subunit of PKA. The model predicts that the U_S3 protein kinase activates PKA, and that either PKA or both PKA and U_S3 enzymes block apoptosis.