Phosphoprotein Phosphatase Activity Associated with Estrogen-Induced Protein in Rat Uterus

Abstract
Estrogen-induced protein was purified from rat uteri and assayed for several enzymatic activities involved in the metabolism and action of cyclic nucleotides. No adenylate and guanylate cyclase (EC 4.6.1.1 and 4.6.1.2, respectively), protein kinase (EC 2.7.1.33) and cyclic nucleotide binding activities could be demonstrated in 3 independent preparations of the protein. All 3 preparations exhibited significant phosphoprotein phosphatase activity (EC 3.1.3.16) on phosphorylated protamine and histones Fl. This activity is optimal at neutral pH, inhibited by Zn2+, and unaffected by cyclic AMP or cyclic GMP.