Hinge and amino-terminal sequences contribute to solution dimerization of human progesterone receptor

摘要: We and others have shown previously that progesterone receptors (PR) form homodimers in solution the absence of DNA dimers are preferential receptor binds with high affinity to target DNA. To determine sequence regions involved homodimerization, wild type PR truncated proteins were expressed an insect baculovirus system. The expression constructs included ligand-binding domain [LBD, amino acids (aa) 688-933], LBD plus hinge (hLBD, aa 634-933), hLBD DNA-binding (DhLBD, 538-933), full- length A B isoforms PR. PR-PR interactions detected by three methods, coimmunoprecipitation fragments full-length PR-A, pull-down PR-polypeptides polyhistidine-tagged versions same polypeptides immobilized metal columns cooperative assays (Hill coefficient, n(H) > 1 indicating interaction). By all assays, alone was not sufficient mediate protein-protein interaction. However, did exhibit other properties ascribed this domain, including binding steroids a relatively good specificity, ligand-induced conformational changes at carboxyl terminus tail heat shock protein 90 its dissociation response hormone. Thus, failure dimerization does appear be due extensively misfolded or unstable polypeptide. minimal carboxyl-terminal fragment capable mediating interaction construct. chromatography assay, self-association PR-A 3.5-fold more efficient than either DhLBD constructs. An amino-terminal (aa 165-535) lacking hinge, found physically associate another LBD, but retaining domain. These results provide evidence for direct exhibited wild-type as compared overall paper consistent conclusion is multiple regions, sequences, contribute directly indirectly homodimerization