[Studies on the prostaglandin E2 receptor in human corpora lutea (author's transl)].

It is known that Prostaglandins (PGs) have a specific effect on the corpus luteum function. In this paper we have studied the physical and chemical characteristics of PGE2 receptor in human corpora lutea to explain the mechanism on corpus luteum function. The presence of PGs binding sites in corpora lutea has been reported, but hardly any papers are available on the presence of PGE2 binding sites in human corpora lutea. The present study was undertaken to determine, using the proportion graph method, whether PGE2 receptors are present in human corpora lutea or not. The number of binding sites and association constant of PGE2 receptor to human corpora lutea of the luteal phase of the cycle and gestation were examined. There is evidence (1) that PGE2 receptors were present in human corpora lutea, and the binding sites have one specific and one non-specific binding system. (2) That the number of binding sites in early, mid and late luteal phase corpora lutea were respectively 105-157, 190-196, 162-190 f moles/mg protein. Association constants were 2.0-12.0 x 10(11) M-1. (3) That the number of binding sites of 6th week gestation corpora lutea were 98-100 f moles/mg protein, and those of 12th week gestation were 40-85 f moles/mg protein. Association constants of the gestation corpora lutea were 17.0-20.0 x 10(11) M-1.