POSSIBLE NUCLEAR FUNCTIONS OF THE MAJOR MOLECULAR CHAPERONES OF THE EUKARYOTIC CYTOPLASM, HSP90

Recent studies suggest that the chaperone function of the 90 kDa heat- shock protein, Hsp90, is restricted to help folding of nuclear hormone receptors, numerous protein kinases and damaged cytosolic proteins af ter proteotoxic stress, Hsp90, the most abundant chaperone of eukaryot ic cytosol, may also participate in formation of cytoarchitecture and direction of cytoplasmic traffic of macromolecules. However, a small, but significant portion of Hsp90 translocates to the nucleus accompany ing steroid receptors and after cellular stress, Here we summarize our present knowledge on the nuclear functions of Hsp90, and raise some s uggestions for its putative role in the organization of the interphase nucleus and mit otic chromosomes.