Protein phosphatases possibly involved in rat spermatogenesis.

The expression of mRNAs for catalytic subunits of serine/threonine protein phosphatases 1 (PP-1) and 2A (PP-2A) in various rat tissues were examined. Four kinds of probes were used to detect mRNAs for two isotypes of PP-1 (dis2m1 and dis2m2), and two isotypes of PP-2A (PP-2A alpha and PP-2A beta). mRNAs for all of these four catalytic subunits were expressed in almost all tissues at substantial levels. They were expressed in two different sizes in most tissues. Remarkable evidence is that the smaller sized mRNAs of dis2m1 and PP-2A beta, 1.8 kb and 1.4 kb in length, respectively, were specifically highly expressed in testis. Both these smaller sized mRNAs began to be expressed at the age when meiosis started and were detected in testicular germ cells at the pachytene stage of meiotic prophase. Protein phosphatases which have peptides encoded by dis2m1 and PP-2A beta as catalytic subunits may play important roles in spermatogenesis.