Hsp90 can Accommodate the Simultaneous Binding of the FKBP52 and HOP Proteins
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1Department of Chemistry, University of Texas at El Paso, 500 W. University Ave, El Paso, Texas 79968, U.S.A
2Border Biomedical Research Center, University of Texas at El Paso, 500 W. University Ave, El Paso, Texas 79968, U.S.A.
Received: February 23, 2011; Accepted: February 28, 2011; Published: February 28, 2011;
Ricardo A. Bernal, e-mail:
The regulation of steroidogenic hormone receptor-mediated activity plays an important role in the development of hormone-dependent cancers. For example, during prostate carcinogenesis, the regulatory function played by the androgen receptor is often converted from a growth suppressor to an oncogene thus promoting prostate cancer cell survival and eventual metastasis. Within the cytoplasm, steroid hormone receptor activity is regulated by the Hsp90 chaperone in conjunction with a series of co-chaperone proteins. Collectively, Hsp90 and its binding associates form a large heteromeric complex that scaffold the fully mature receptor for binding with the respective hormone. To date our understanding of the interactions between Hsp90 with the various TPR domain-containing co-chaperone proteins is limited due to a lack of available structural information. Here we present the stable formation of Hsp902-FKBP521- HOP2 and Hsp902-FKBP521-p232-HOP2 complexes as detected by immunoprecipitation, time course dynamic light scattering and electron microscopy. The simultaneous binding of FKBP52 and HOP to the Hsp90 dimer provide direct evidence of a novel chaperone sub-complex that likely plays a transient role in the regulation of the fully mature steroid hormone receptor.
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