Cellular localization of the Mn2+-dependent adenylyl cyclase (AC) in rat testis.

In the present study we have examined the exact cellular localization of the Mn2+-dependent adenylyl cyclase (AC) in the rat testis. Several pieces of evidence indicate that this testis specific enzyme is exclusively localized to haploid cells in the testis: firstly, the appearance of Mn2+-dependent adenylyl cyclase coincides in time with the occurrence of haploid cells (IC) in the rat testis. Secondly, tests of tfm rats and mice, in which little or no haploid cells are found, exhibit negligible Mn2+-dependent AC activity. Finally, separation of various testicular cells by BSA gradient sedimentation (Staput fractionation), revealed that this enzyme activity follows the location of haploid cells; the highest specific AC activities being found in the fractions containing elongated spermatids. Some activity found in the primary spermatocyte fraction (4C cells) can to a large extent be explained by the contamination of haploid cells in this fraction.