|Budget Amount *help
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1989: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1988: ¥1,700,000 (Direct Cost: ¥1,700,000)
The structure of LH/HCG receptor of rat luteal cells was investigated using different two types of cross linkers. Rat luteal cells obtained from Parlow rats were incubated with hCG whose alpha-subunit or beta-subunit is labeled with ^<125>I. hCG-receptor complex was cross linked from inner side by Photoaffinity labeling (ABG) and from outer side by SES. After solubilized with SDS, reduced with DTT, the cross-linked samples were applied on SDS-PAGE and observed by autoradiography. When ^<125>I-alpha+beta was used, 4 complexes, A(MW 136k), B(105k), C(78k), D(72k) were found by ARG and 3 complexes, A(136k), B(105k), C(78k) by SES. When alpha+^<125>I-beta was used, 4 complexes A(136k), B(116k), C(90k), D(72k) were found by ABG and strong A(136k) and weak D(72k) by SES. From these results it was suggested that LH/hCG receptor is composed of several proteins and that the binding mechanism of hCG to its receptor is such that the alpha subunit is contained within the beta subunit.
In the following experiments we investigated the effects of progesterone or anti-progesterone on the structure of the LH/hCG receptor. Specific binding capacity of the ovaries to LH/hCG were studied in D7 pregnant rats treated with RU 1mg/kg alone (RU group) or with both RU 1mg/kg and progesterone 50mg/kg (RU+P group). The specific binding, of LH/hCG to ovarian homogenates decreased significantly after 72 hours in the RU group. But in the RU+P grolip, the specific bindings were kept at the sante levels as the controls. Scatcliard analysis of these restilts disclosed that in the RU group, both affinity and numbers of receptors decreased compared to the controls, and that in the RU+P group only affinity decreased transiently and afterwards recovered quickly. From these results it was concluded that the structure of LH/hCG receptors of rat luteal cells are not changed by propesterone or anti--progesterone but changed in those number and affinity.