Protein kinase activity of purified components of the chicken oviduct progesterone receptor.

Preparations of the 90K and 110K components of the chick oviduct progesterone receptor (PR) purified to near homogeneity were tested for protein kinase activity. The 90K component was shown to incorporate radioactive phosphate from [gamma-32P]-ATP in the presence of Ca2+ but not of Mg2+ ions, while the 110K component was phosphorylated in the presence of Mg2+, but not of Ca2+. The enzymatic activity of the 90K polypeptide appeared selective, since added proteins (histones) did not become phosphorylated. However, all proteins present in the 110K preparations were phosphorylated in the presence of Mg2+. These data suggest that components of the chick oviduct PR display protein kinase activity.