Localization and structures of plasma membrane estrogen receptor

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1. Localization of plasma membrane estrogen receptor (M-ER)By using post-embedding method, M-ER was localized with anti-ERα antibodies in the mouse uterus and MCF-7 human breast cancer cells after estrogen stimulation. ERα immunoreaction was detected on the chromatin in the uterine epithelial cells and MCF-7 cells and intranuclear translocation of ERα was not observed after estrogen stimulation. In MCF-7 cells, reaction was also present in the cytoplasm and on the plasma membrane, although the labeling density in the nucleus, cytoplasm and plasma membrane was different in each cell, suggesting heterogeneous cell cycles. Labeling density of ERα on the cell membrane appeared to increase at 15 min after the stimulation. Quantitative study is being carried out now.2. Analysis of ERα by western blotting.After estrogen stimulation, ERα in MCF-7 cells was analyzed. There were no significant difference in ERα expression patterns concerning concentrations and molecular weights from 0 to 60 min after stimulation : 65 and 37 kD polypeptides reacted with ERα antibodies in all samples.3. Expression of MAPKAfter estrogen stimulation, MAPK/ERK expression was examined by the western blotting. Concentration of ERK 1,2 was almost constant from 0 to 60 min, but that of phosphorylated ERK 1,2 increased at 15 and 30 min after the stimulation.