THE CYCLOSPORINE A-BINDING IMMUNOPHILIN CYP-40 AND THE FK506-BINDING IMMUNOPHILIN HSP56 BIND TO A COMMON SITE ON HSP90 AND EXIST IN INDEPENDENT CYTOSOLIC HETEROCOMPLEXES WITH THE UNTRANSFORMED GLUCOCORTICOID RECEPTOR
THE CYCLOSPORINE A-BINDING IMMUNOPHILIN CYP-40 AND THE FK506-BINDING IMMUNOPHILIN HSP56 BIND TO A COMMON SITE ON HSP90 AND EXIST IN INDEPENDENT CYTOSOLIC HETEROCOMPLEXES WITH THE UNTRANSFORMED GLUCOCORTICOID RECEPTOR
复制标题
DOI：
10.1074/jbc.270.35.20479
复制
发表时间：
1995-09-01
影响因子：
4.8
通讯作者：
PRATT, WB
中科院分区：
文献类型：
--
作者：
OWENSGRILLO, JK;HOFFMANN, K;PRATT, WB
我们最近已经证明了HSP56，FKBOG结合的免疫亲和素成分，两者都是热休克蛋白(HSP90)。热休克蛋白70。Hsp56)异复合体和未转化的糖皮质激素受体异复合体直接与HSP90结合(Zachar，M.J.，Owens-Grillo，J.K.，Dittmar，K.D.，Hutchison，K.A.，Zacharek，A.M.，Leach，K.L.，Deibel，M.R.和Pratt，W.B.(1994)J.Biol。化学。269、11155-11161)。在这项工作中，我们证明了未转化的糖皮质激素受体和HSP90异源复合体都含有CYP-40，这是一种环孢素A结合类的40 kDa免疫亲和素。CYP-40存在于天然糖皮质激素受体异源复合体和兔网织红细胞裂解物重组的受体异源复合体中，并且受体异源复合体中CYP-40的存在被钼酸盐稳定。从细胞裂解液中免疫吸附HSP90产生HSP56和CYP-40的共免疫吸附，表明这两种免疫亲和素都是与HSP90天然的异源复合体。然而，HSP56的免疫吸附不会产生CYP-40的共免疫吸附；因此，这两种免疫亲和素不存在于与HSP90的同一异构体中。纯化的CYP-40和HSP56都直接与纯化的HSP90结合，过量的CYP-40阻止HSP56的结合，这与HSP90上存在共同的免疫亲和素结合位点是一致的。我们的数据还表明，至少存在两种类型的未转化的糖皮质激素受体-HSP90异源复合体，一种含有HSP56，另一种含有CYP-40。免疫亲和素在类固醇受体作用中的作用尚不清楚，但很明显，免疫亲和素的肽基丙酰异构酶活性不是糖皮质激素受体-HSP90异源复合体组装和网织红细胞裂解物HSP90相关蛋白折叠系统正确折叠激素结合结构域所必需的。
We have recently shown that hsp56, the FKBOG-binding immunophilin component of both the heat shock protein (hsp90 . hsp70 . hsp56) heterocomplex and the untransformed glucocorticoid receptor heterocomplex, is bound directly to hsp90 (Czar, M. J., Owens-Grillo, J. K., Dittmar, K. D., Hutchison, K. A., Zacharek, A. M., Leach, K. L., Deibel, M. R., and Pratt, W. B. (1994) J. Biol. Chem. 269, 11155-11161). In this work, we show that both untransformed glucocorticoid receptor and hsp90 heterocomplexes contain CyP-40, a 40-kDa immunophilin of the cyclosporin A-binding class. CyP-40 is present in both native glucocorticoid receptor heterocomplexes and receptor heterocomplexes reconstituted with rabbit reticulocyte lysate, and the presence of CyP-40 in the receptor heterocomplex is stabilized by molybdate. Immunoadsorption of hsp90 from cell lysate yields coimmunoadsorption of both hsp56 and CyP-40, showing that both immunophilins are in native heterocomplex with hsp90. However, immunoadsorption of hsp56 does not yield coimmunoadsorption of CyP-40; thus, the two immunophilins do not exist in the same heterocomplex with hsp90. Both purified CyP-40 and hsp56 bind directly to purified hsp90, and excess CyP-40 blocks the binding of hsp56, consistent with the presence of a common immunophilin binding site on hsp90. Our data also suggest that there are at least two types of untransformed glucocorticoid receptor-hsp90 heterocomplexes, one that contains hsp56 and another that contains CyP-40. The role played by the immunophilins in steroid receptor action is unknown, but it is clear that the peptidylprolyl isomerase activity of immunophilins is not required for glucocorticoid receptor-hsp90 heterocomplex assembly and proper folding of the hormone binding domain by the hsp90-associated protein folding system of reticulocyte lysate.