Characteristics of a maturation-including steroid receptor in the plasma membrane of xenopus oocytes

Xenopus laevis is a widely used animal in general and molecular biology research (Dawid and Sargent, 1988). This animal can be conveniently maintained under laboratory conditions and its ovarian foUicle cells are easily dissociated from its relatively large oocytes using well estabhshed methods. Thus, a considerable amount of background information on developmental and molecular biology of oocytes in this species has already been accumulated.

The Xenopus oocyte was one of the first and most convincing models establishing the existence of ceU surface actions of steroids (Haukkamaa, 1987). However, our knowledge on the characteristics of the MIS receptor in the plasma membrane of Xenopus oocytes has feUed to make significant progress (Jessus and Ozon, 1993), due in part to the lack of adequate techniques for determination of receptor binding activity and for isolation and purification of the receptor. Therefore, the specific objectives of this research are to develop a direct radioreceptor assay technique for the MIS receptor of Xenopus oocyte membranes, to study the characteristics of MIS receptor binding activity and the developmental and gonadotropic regulation of MIS receptor density, and to isolate and purify the MIS receptor. In Chapter 2, the development of MIS receptor binding assay technique and characterization of the receptor binding activity is described; this chapter has been published in the joumal Biology of Reproduction (1993; 49: 980-988). In Chapter 3, the isolation and purification of a protein tentatively identified as the MIS receptor is described. In Chapter 4, an overall summary and conclusion is provided.