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KMID : 1161520010050010051
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Animal Cells and Systems
2001 Volume.5 No. 1 p.51 ~ p.57
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Visualization of progesterone binding to plasma membrane of xenopus oocytes
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Ju Jung-Won
Im Wook-Bin
Kwon Hyuk-Bang
Choi Hueng-Sik
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Abstract
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We have previously shown that oocyte maturation is induced by an immobilized progesterone, progesterone?3?carboxymethyloxime ? bovine serum albumin conjugate (P?BSA) in Rana dybowskii. In this study, we confirmed the maturation inducing activity of P?BSA on Xenopus oocyte and examined the binding character of the immobilized progesterone on the surface of Xenopus oocytes after removal of the vitelline layer. P?BSA induced maturation of Xenopus oocytes but E?BSA failed to do so as observed in Rana. Binding of the immobilized progesterone, fluorescein isothiocyanate?labeled progesterone?3?O?carboxymethyloxime?BSA (P?BSA?FITC) on the devitellined oocytes surface was examined by fluorescence confocal microscopy. The binding affinity of P?BSA?FITC to the devitellined oocyte was higher than that of estrogen?BSA?FITC (E?BSA?FITQ or testo?sterone?BSA?FITC (T?BSA?FITC). The binding disappeared in the presence of excess free progesterone but not in the presence of free estrogen. Maximum binding occurred after two?hours of incubation with P?BSA?FITC at pH 7.5. Stronger binding occurred in oocytes at stage VI than stage IV, and in vitro treatment of hCG enhanced the binding. Taken together, these results suggest that a specific receptor for progesterone exists on the plasma membrane of Xenopus oocytes and that progesterone acts initially on this putative receptors and triggers generation of membrane?mediated second messengers during the early stage of oocyte maturation in amphibians.
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KEYWORD
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Nongenomic action, Progesterone, Meiotic maturation, Xenopus oocyte, Amphibian
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