Hsp90
Hsp90 (heat shock protein 90) is a chaperone protein that assists other proteins to fold properly, stabilizes proteins against heat stress, and aids in protein degradation. It also stabilizes a number of proteins required for tumor growth, which is why Hsp90 inhibitors are investigated as anti-cancer drugs.
| Histidine kinase-, DNA gyrase B-, and HSP90-like ATPase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | HATPase_c | ||||||||
| Pfam | PF02518 | ||||||||
| Pfam clan | CL0025 | ||||||||
| InterPro | IPR003594 | ||||||||
| SMART | SM00387 | ||||||||
| SCOP2 | 1ei1 / SCOPe / SUPFAM | ||||||||
| |||||||||
| Hsp90 protein | |||||||||
|---|---|---|---|---|---|---|---|---|---|
Structure of the N-terminal domain of the yeast Hsp90 chaperone. | |||||||||
| Identifiers | |||||||||
| Symbol | Hsp90 | ||||||||
| Pfam | PF00183 | ||||||||
| InterPro | IPR020576 | ||||||||
| PROSITE | PDOC00270 | ||||||||
| SCOP2 | 1ah6 / SCOPe / SUPFAM | ||||||||
| |||||||||
Heat shock proteins, as a class, are among the most highly expressed cellular proteins across all species. As their name implies, heat shock proteins protect cells when stressed by elevated temperatures. They account for 1–2% of total protein in unstressed cells. However, when cells are heated, the fraction of heat shock proteins increases to 4–6% of cellular proteins.
Heat shock protein 90 (Hsp90) is one of the most common of the heat-related proteins. The "90" comes from the fact that it has a mass of roughly 90 kilodaltons. A 90 kDa protein is considered fairly large for a non-fibrous protein. Hsp90 is found in bacteria and all branches of eukarya, but it is apparently absent in archaea. Whereas cytoplasmic Hsp90 is essential for viability under all conditions in eukaryotes, the bacterial homologue HtpG is dispensable under non-heat stress conditions.
This protein was first isolated by extracting proteins from cells stressed by heating, dehydrating or by other means, all of which caused the cell's proteins to begin to denature. However it was later discovered that Hsp90 also has essential functions in unstressed cells.