Characterization of a novel 23-kilodalton protein of inactive progesterone receptor complexes. Mol Cell Biol

Department of Biochemistry and Molecular Biology, Mayo Graduate School, Rochester, Minnesota 55905.
Molecular and Cellular Biology (Impact Factor: 4.78). 04/1994; 14(3):1956-63. DOI: 10.1128/MCB.14.3.1956
Source: PubMed


Immunoprecipitation of unactivated avian progesterone receptor results in the copurification of hsp90, hsp70, and three additional proteins, p54, p50, and p23. p23 is also present in immunoaffinity-purified hsp90 complexes along with hsp70 and another protein, p60. Antibody and cDNA probes for p23 were prepared in an effort to elucidate the significance and function of this protein. Antibodies to p23 detect similar levels of p23 in all tissues tested and cross-react with a protein of the same size in mice, rabbits, guinea pigs, humans, and Saccharomyces cerevisiae, indicating that p23 is a conserved protein of broad tissue distribution. These antibodies were used to screen a chicken brain cDNA library, resulting in the isolation of a 468-bp partial cDNA clone encoding a sequence containing four sequences corresponding to peptide fragments isolated from chicken p23. This partial clone was subsequently used to isolate a full-length human cDNA clone. The human cDNA encodes a protein of 160 amino acids that does not show homology to previously identified proteins. The chicken and human cDNAs are 88% identical at the DNA level and 96.3% identical at the protein level. p23 is a highly acidic phosphoprotein with an aspartic acid-rich carboxy-terminal domain. Bacterially overexpressed human p23 was used to raise several monoclonal antibodies to p23. These antibodies specifically immunoprecipitate p23 in complex with hsp90 in all tissues tested and can be used to immunoaffinity isolate progesterone receptor complexes from chicken oviduct cytosol.

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Available from: Jill L Johnson, Jun 29, 2015
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    • "Hsp90 is required for the activation and stabilization of several signaling proteins, referred to as client proteins of Hsp90. The acidic 23-kDa protein p23 was first identified as a component of the progesterone receptor (PR)–Hsp90 complex (Johnson et al. 1994). Since then, it has come to be widely recognized as a co-chaperone of Hsp90 (Felts and Toft 2003; Pratt and Toft 2003), possessing also passive chaperoning activity itself (Bose et al. 1996) as well as a reported prostaglandin synthase activity (Tanioka et al. 2000). "
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