Molecular cloning and expression of cDNAs encoding two isoforms of protein phosphatase 2C beta from mouse testis.

Two isoforms of protein serine/threonine phosphatase were isolated and sequenced from mouse testis. A deletion of 48 nucleotides of PP2C beta 4 cDNA in comparison with PP2C beta 3 cDNA resulted in different COOH-terminal sequences of 12 and 15 amino acids, respectively. These COOH-terminal sequences of PP2C beta 3 and PP2C beta 4 were further found to be different from those of isoforms MPP beta 1 and MPP beta 2 of mouse PP2C beta reported (Terasawa, et al. Arch. Biochem. Biophys. 307: 342-349, 1993). The common sequence of 378 amino acids from these four isoforms of mouse PP2C beta exhibited 95% identity with the corresponding sequence of rat PP2C beta. The mRNAs of approximately 2.0 Kb for PP2C beta 3 and PP2C beta 4 were expressed only in testis, while the mRNAs of 3.3 Kb and 8.5 Kb for MPP beta 1 and MPP beta 2, respectively, were found in somatic tissues.