| Hsp Familya |
Hsp Structure and Function |
References |
| sHsps |
Multimeric complexes composed of monomers containing an amino-termial region, an α-crystallin domain and a carboxyl-extension; the domains cooperate in oligomerization and substrate binding.
Prevent stress-induced irreversible protein
denaturation; inhibit apoptosis; ATP independent. |
[4,23,24,26,27,32] |
| Hsp70 |
Monomeric protein with a conserved ATP binding /hydrolysis site in the amino-terminus, a linker region and a variable carboxyl substrate-binding domain.
Binds and folds nascent and denaturing proteins; protects against stresses such as bacterial infection. |
[35,36,38,40] |
| Hsp90 |
Dimeric protein; each monomer has an amino-terminal domain that hydrolyzes ATP, a substrate–binding middle domain and a carboxyl-domain that interacts with co-chaperones.
Folds nascent and denaturing proteins; interacts with kinases and other regulatory molecules; protein degradation. |
[43-46,49] |
| Hsp60 (chaperonin,
TRiC, CCT) |
Two back-to-back rings of eight to nine subunits each with an apical capped domain that binds substrate, an equatorial region with an ATP hydrolysis site and a linking domain.
Binds substrates via hydrophobic, polar and charged residues; required by actin and tubulin for folding. |
[51,52,54-56,58] |
aThe Hsps are described separately but they function as co-operative networks to maintain protein homeostasis within cells, either during normal growth or upon
exposure to stress such as heat, salinity, toxins and infection. |
