A Membrane Receptor Mechanism for Steroid Hormones Reinitiating Meiosis in Xenopus Laevis Oocytes*: (progesterone/receptor/adenylate cyclase/protein kinase/membrane).

There is a membrane progesterone receptor in Xenopus laevis oocytes that undergo meiosis under steroid exposure. Early responses include a decrease of leucine uptake, a decrease of adenylate cyclase and alkaline phosphatase activities, and a decrease of the phosphorylation of a specific p48 protein in the membrane. These results are compatible with a decrease of membrane fluidity brought about by the hormonal message. However the above-cited effects as well as the Ca2+ -changes are not yet enough well understood to be able to precisely delineate their role in meiosis reinitiation.