cDNAs of RAC protein kinases (RAC-PK) alpha and beta were cloned from a rat testis cDNA library. The predicted open reading frames encode 480 and 481 amino acids of RAC-PK alpha and beta, respectively, and the rat RAC-PK alpha and beta have sequences conserved among different mammalian species such as the pleckstrin homology domain at their amino-terminal region and the protein-serine/threonine kinase catalytic domain at their carboxyl-terminal region. RNA blot analysis showed wide distribution of two RAC-PK in rat tissues. Immunoprecipitation analysis revealed that RAC-PK alpha and beta associate with protein kinase C zeta through the pleckstrin homology domain in vitro, suggesting the interaction between RAC-PK and protein kinase C.