Protein-protein interactions that precede the nuclear entry of goat uterine estrogen receptor under cell-free conditions.
Mechanisms associated with a regulated nuclear entry of the goat uterine estrogen receptor (gER), under the influence of estradiol, have been examined using a cell-free system. The gER transport into the nucleus is mediated by a 55-kDa cytosolic protein, p55. Experimental evidence has been provided to demonstrate that p55 binds to the nuclear localization signals (NLS) on the gER. Under hormone-free conditions, a 28-kDa protein, p28, binds to the NLS and prevents the p55 interaction with the NLS. This inhibition is reversed by a 73-kDa protein, p73. It appears that p73 associates with the hormone binding domain (HBD) of the gER under hormone-free conditions. Estradiol binding to the HBD facilitates p73 interaction with p28. This leads to the dissociation of p28 from the NLS, which, in turn, facilitates the binding of p55 to the NLS on the gER. Both p28 and p55 cross-react with monoclonal antibodies against hsp-25 and hsp-70, indicating a possibility that p28 and p55 belong to a superfamily of molecular chaperones. J. Cell. Biochem. 78:650-665, 2000.
Sai Padma
A
A
Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram 695014, Kerala, India.
Renil
M
M
Varman Thampan
R
R
D000199:Actins / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism*; D002474:Cell-Free System; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D003600:Cytosol / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004958:Estradiol / Q000378:metabolism; D005260:Female; D016147:Genes, Tumor Suppressor; D006041:Goats; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D007700:Kinetics; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011960:Receptors, Estrogen / Q000378:metabolism*; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D014599:Uterus / Q000378:metabolism*
D000199:Actins; D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D011960:Receptors, Estrogen; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D004958:Estradiol