Homma H, Maruyama H, Niitsu Y, Listowsky I
Biochem J. 1986 May 1;235(3):763-8. doi: 10.1042/bj2350763.
The distribution of glucocorticoids incubated with rat liver cytosol preparations or administered in vivo to adrenalectomized rats was analysed by chromatographic procedures. Corticosterone or dexamethasone was co-eluted with Yb-type GSH S-transferases in anion-exchange and gel-permeation chromatography systems, and these glucocorticoids also were bound to Yb forms in analyses by immunoadsorbent and lysyl-GSH affinity matrices. Pretreatment of cytosol with lysyl-GSH to extract GSH S-transferases or incubation with excess bilirubin, which is expected to compete with steroids for binding to the protein, yielded preparations that were devoid of this major steroid-binding component. In mixtures of the multiple rat GSH S-transferases, corticosterone preferentially interacted with Yb forms rather than Ya and Yc subgroups. All of the multiple Yb forms resolved by chromatofocusing procedures retained the steroid-binding capacity. It is suggested that these abundant proteins can account for a considerable share of intracellular glucocorticoid binding and represent a high-affinity non-saturable binding component with potential to function in steroid-hormone metabolism and action.
通过色谱程序分析了与大鼠肝细胞溶胶制剂一起孵育或体内给予肾上腺切除大鼠的糖皮质激素的分布情况。在阴离子交换和凝胶渗透色谱系统中，皮质酮或地塞米松与Yb型谷胱甘肽S-转移酶共洗脱，并且在通过免疫吸附和赖氨酰-谷胱甘肽亲和基质进行的分析中，这些糖皮质激素也与Yb形式结合。用赖氨酰-谷胱甘肽预处理细胞溶胶以提取谷胱甘肽S-转移酶，或与过量胆红素孵育（预期胆红素会与类固醇竞争与蛋白质的结合），得到的制剂缺乏这种主要的类固醇结合成分。在多种大鼠谷胱甘肽S-转移酶的混合物中，皮质酮优先与Yb形式相互作用，而不是与Ya和Yc亚组相互作用。通过色谱聚焦程序分离的所有多种Yb形式都保留了类固醇结合能力。有人提出，这些丰富的蛋白质可以占细胞内糖皮质激素结合的相当大比例，并代表一种具有高亲和力的非饱和结合成分，有可能在类固醇激素代谢和作用中发挥作用。
