Table 1.
Summarized information on heat shock protein (HSP) family members.
| Family | Primary members | Location | Characteristics | Functions | Refs. |
|---|---|---|---|---|---|
| Large HSPs | HSP110 GRP170 |
Cytosol ER |
ATP-dependent highly conserved bilobate 40 KDa nucleotide-binding domain, belonging to HSP70 superfamily. ATP-dependent nucleotide binding domain with carboxyl terminus similar to HSP110, belonging to the HSP70 superfamily. |
Cochaperson of HSP70: holdase to prevent protein aggregation. | [7] |
| Small HSPs | HSPB1 HSPB2 HSPB3 HSPB4 HSPB5 HSPB6 HSPB7 HSPB8 HSPB9 HSPB10 |
Cytosol | ATP-independent large heterogeneous oligomers. | Holdase to inhibit protein aggregation and sequester misfolded proteins. | [8] |
| HSP60 | HSP60 TRiC |
Mitochondria Cytosol |
ATP-dependent double ring structure containing two heptameric rings of HSP60. ATP-dependent double ring structure containing two octameric rings of TRiC. |
Foldase to prevent protein aggregation. | [9] |
| HSP40 | DNAJA DNAJB DNAJC |
Cytosol Mitochondria Nucleus |
J Domain containing proteins interacting with HSP70. | Cochaperon of HSP70: hold misfolded proteins, recruit HSP70, regulate HSP70 ATPase activity. | [10] |
| HSP70 | HSPA1A/1B HSPA1L HSPA2 HSPA5 HSPA6 HSPA7 HSPA8 HSPA9 HSPA12A/12B HSPA13 HSPA14 |
Cytosol Nucleus ER Mitochondria |
ATP-dependent conserved structure containing NTD-SBD domains; chaperon function is based on the allosteric conformation change cycle. | Cochaperon of HSP90: foldase to prevent protein aggregation; triage protein fates. | [10] |
| HSP90 | HSP90AA HSP90AB GRP9 TRAP1 |
Cytosol Cytosol Cytosol/ER Mitochondria |
ATP-dependent homodimers; chaperon function is based on the allosteric conformation change cycle. | Foldase for newly synthesized or misfolded proteins. | [11] |
HSP: heat shock protein; GRP: Glucose-Regulated Protein; ATP: adenosine triphosphate; NTD: N-terminal domain; SBD: Substrate Binding Domain; ER: endoplasmic reticulum; TRiC: TCP-1 Ring Complex; ATPase: adenosine triphosphatase; HSPA: heat shock protein family A; HSPB: heat shock protein family B; DNAJA: DnaJ (Hsp40) Homologue, Subfamily A; HSPA1A/1B: heat shock protein Ffamily A (Hsp70) Member 1A/1B; HSP90: heat shock protein 90; TRAP1: tumour necrosis factor receptor associated protein 1.