YEAST EXPRESSION OF HUMAN MEMBRANE PROGESTERONE RECEPTORS.

Progesterone is a hormone indispensable for pregnancy maintenance that acts through two pathways: via nuclear receptors it regulates gene expression while via membrane receptors it exerts quick nongenomic effects. Activation of spermatozoa and oocytes are among such nongenomic effects. Human membrane progesterone receptors (hmPRs) have been cloned, however, their hormone binding features are still weakly characterized. The knowledge of these features is a prerequisite for design of selective progesterone analogs that might be applied in obstetrics, gynecology, and also in oncology. In order to develop a system for the analysis of hmPRs ligand-binding properties, we constructed expression plasmid vectors containing nucleotide sequence insert encoding for the isoform alpha of hmPR under the yeast GAL1 promoter. The transfection of yeast strains with the constructs thus obtained gave an appearance of hmPRalpha mRNA in the cells, while cellular extracts containing membrane fractions acquired an ability for saturable binding of 3H-progesterone. Analogous vectors were constructed for expression of isoforms beta and gamma of hmPR. The results create a methodical base for selection of agents (agonists and antagonists) targeted preferably or exclusively to membrane progesterone receptors. [ABSTRACT FROM AUTHOR]