Abstract
Human chorionic gonadotrophin (hCG) is capable of stimulating adenylate cyclase activity in homogenates of luteinized rat ovarian tissue. hCG from which the sialic acid residues have been removed by treatment with neuraminidase (asialo-hCG) has approximately 12% of the activity of the intact hormone. Neither the a nor the β subunits of hCG caused any stimulation of the enzyme. An adenylate cyclase system is also present in fractions sedimenting with operationally-defined nuclei, mitochondria, and micro-somes. The enzyme in these fractions is not stimulated by hCG.