Table 3.
List of molecular chaperones, co-chaperones, their localization and functions.
| Chaperonin | Organism | Chaperone | Co-Chaperone | Localization | Functions |
|---|---|---|---|---|---|
| HSP60/ HSPD1 |
Bacterial | GroEL | GroES | Cytosol | Assist folding and refolding of denatured proteins |
| Mammalian | mHSP60 (HSPD)/ TriC/CCT |
HSP10 (HSPE) | Mitochondria, cytosol | Folding of nascent proteins and mitochondria proteostasis | |
| HSP40/HSPF | Bacterial | DnaJ | DnaK/GrpE | Cytosol | Modulating activity of DnaK, associated with nascent polypeptides, binds to unfolded proteins |
| Mammalian | Hdj1/2, HSP40, auxilin |
HSP70/HIP | Cytosol | Modulating ATPase activity of DnaK, auxilin recruits HSP70 partner HSC70 to uncoat clathrin-coated vesicles | |
| HSP70/HSPA | Bacterial | DnaK | DnaJ/GrpE/ClpB | Cytosol | Folding and export of nascent peptides, disaggregation and degradation of stress-induced folding and translocation |
| Mammalian | Bip/Grp78 | DnaJ-like ER proteins (Grp70, Sil1/sls1) | Endoplasmic reticulum | Involved in calcium homeostasis, translocation, folding, transport and re-translocation of polypeptides, regulation of unfolded protein response | |
| HSC70 (HSP73), HSP70 (HSP72) | HSP40, Hop, Bag1-5, HIP, HSPBP1, CHIP, SGT, HSP110, Homologs to Tom 70, TPR1 | Cytosol | Folding and transportation of nascent polypeptide, inhibits mis-folding and aggregations | ||
| mHSP70/Grp75/mortalin | - | Cytosol | Protein folding and translocation into mitochondria | ||
| HSP90/HSPC | Bacterial | HtpG | - | Cytosol | Stress-responsive protein folding |
| Mammalian | HSP90/83/89, TRAP1/2 | HOP/HIP, HSP70, p50, p23, CHIP, Sgt1/TPR2, Immunophilins | Cytosol, mitochondrial |
Folding and conformational regulation of signaling protein, regulation of steroid hormone receptor and kinases | |
| Grp94 | Grp78 | ER | Folding and assembly of secretary proteins | ||
| HSP100/HSPH | Bacterial | ClpA | ClpP, SspB | Cytosol | ATP dependent protein unfolding and proteolysis |
| ClpB | Dnak, DnaJ, GrpE | Cytosol | ATP dependent processing of aggregated proteins. | ||
| Small HSPs (HSPB) | Bacterial | IbpA/IbpB | - | Cytosol | Associated with inclusion bodies, prevent heat denatured protein aggregation |
| Mammalian | α-crystallin, HSP27 | - | Cytosol | Prevent heat denatured protein aggregation, regulate microfilament polymerization | |
| Chaperones | Bacterial | HSP33, SecB | SecA | Cytosol | Prevent aggregation of oxidative damage proteins. Shuttling of secretory proteins SecA/B, maintenance of periplasm proteins, Pili assembly |
| SKP/PapD/FimC | PapC, FimD | Periplasm | |||
| Mammalian | Calnexin, calreticulin, PDI, HSP47 (collagen) | ERp57, Cnx/Crt | Endoplasmic reticulum (ER) | Folding of ER glycosylated proteins (Cnx/Crt); collagen biosynthesis (HSP47), assist di-sulfide bond formation. |