InterPro domain: IPR020575

Prokaryotes and eukaryotes respond to heat shock and other forms of environmental stress by inducing synthesis of heat-shock proteins (hsp) [ 1 ]. The 90kDa heat shock protein, Hsp90, is one of the most abundant proteins in eukaryotic cells, comprising 1-2% of cellular proteins under non-stress conditions [ 2 ]. Its contribution to various cellular processes including signal transduction, protein folding, protein degradation and morphological evolution has been extensively studied [ 3 , 4 ]. The full functional activity of Hsp90 is gained in concert with other co-chaperones, playing an important role in the folding of newly synthesised proteins and stabilisation and refolding of denatured proteins after stress. Apart from its co-chaperones, Hsp90 binds to an array of client proteins, where the co-chaperone requirement varies and depends on the actual client.

The sequences of hsp90s show a distinctive domain structure, with a highly-conserved N-terminal domain separated from a conserved, acidic C-terminal domain by a highly-acidic, flexible linker region.

1. The heat-shock proteins. Annu. Rev. Genet. 22, 631-77
2. Hsp90 isoforms: functions, expression and clinical importance. FEBS Lett. 562, 11-5
3. Hsp90 chaperonins possess ATPase activity and bind heat shock transcription factors and peptidyl prolyl isomerases. J. Biol. Chem. 268, 1479-87
4. Assisting spontaneity: the role of Hsp90 and small Hsps as molecular chaperones. Trends Biochem. Sci. 19, 205-11