ニジマス肝臓におけるエストロゲン結合部位

概要

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^3H-Estradiol-17β was predominantly distributed in the cytosol and nuclear fractions when the steroid hormone was incorporated into liver cells of mature female rainbow trout in vitro. ^3H-Estradiol-bound 4s receptor complex (K_a=1.3×10^8 M^<-1>) was detected in the liver cytosol. A little seasonal variation and sex difference on the estradiol binding were observed in the cytosol receptor fraction of trout liver at various spawing seasons. The female specific and seasonal variable nuclear bindings were found only by the incubation of the isolated nuclei or chromatin with free ^3H-estradiol. The nuclear binding determined in the mature female trout liver shows high binding affinity (K_a=5.7×10^7 M^<-1>) and high binding site (7 pmol/mg protein). ^3H-Estradiol-receptor complex faild to bind estradiol to the isolated nuclei and chromatin. It is suggested that the saturable nuclear binding of free estradiol is proportional to the quantity of the receptors translocated from the cytoplasm. Treatment with 0.3M NaCl, 0.1% heparin, phospholipase or DNase faild to release the bound ^3H-estradiol from the nuclei. A 4s molecule bound with ^3H-estradiol was released from the chromatin acceptor sites by protease digestions. The binding process of estrogen into the nuclei in the trout liver is similar to the transport mechanism found in other oviparous and mammalian livers.
群馬大学の論文
1987-02-20