Cellular localization and developmental changes of deoxyribonucleoside-activated nucleotidase in the rat testis.

Specific deoxyribonucleoside-activated nucleotidase (DAN) activity showed a rapid decline during the exponential increase in testis weight between 25 and 35 days of age. Specific DAN activity in Sertoli cells was dependent on the amount of cytosol in the enzyme assay. At optimal cytosol concentration the measured value was 50 units/mg of protein. Specific DAN activity in peritubular cells, primary spermatocytes and round spermatids was 13, 3.7 and 3.1 units/mg, respectively, and was independent of the cytosol concentration in the assay.