In humans, progesterone secretion occurs during the estrous cycle and early pregnancy. Two hormones, luteinizing hormone (LH) and human chorionic gonadotropin (hCG), bind to specific LH receptors on cells in the ovary and promote ongoing hormone release by this gland. Similarities between human and sheep luteal cells make the ewe an excellent model system for studying LH receptor function. The goal of this project is to examine the organization of the LH receptor complex on ovine luteal cells in the non-pregnant animal to learn whether receptor organization affects LH receptor function. Laser-optical techniques will be used to determine hormone binding to the LH receptor leads to receptor self- association or association with other receptors or with other membrane proteins. We will then examine the lipid environment near the LH receptor. As the corpus luteum ages and eventually ceases to function, changes in the lipid environment may result in organizational changes in the LH receptor. These experiments will use a light-activated protein crosslinking agent to explore changes in protein concentration within protein-rich regions of the membrane. //
