cAMP-dependent protein kinase A (PKA) is the best-characterized protein kinases and has served as a model of the structure and regulation of cAMP-binding protein as well as of protein kinases. To determine the function of PKA in development, we employed the yeast two-hybrid system to screen for catalytic subunit of PKA $(Calpha)$ interacting partners in a cDNA library from mouse embryo. A Testis-brain RNA-binding protein (TB-RBP), specifically bound to $Calpha$. This interaction was verified by several biochemical analysis. Our findings indicate that $Calpha$ can modulate nucleic acid binding proteins of TB-RBP and provide insights into the diverse role of PKA.