Co-chaperones are proteins that assist chaperones in protein folding and other functions. Co-chaperones are the non-client binding molecules that assist in protein folding mediated by

Hsp70 The 70 kilodalton heat shock proteins (Hsp70s or DnaK) are a family of conserved ubiquitously expressed heat shock proteins. Proteins with similar structure exist in virtually all living organisms. Intracellularly localized Hsp70s are an importa ...

and

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, ...

. They are particularly essential in stimulation of the ATPase activity of these chaperone proteins. There are a great number of different co-chaperones however based on their domain structure most of them fall into two groups: J-domain proteins and tetratricopeptide repeats (TPR). Co-chaperones assist heat shock proteins in the protein folding process. These co-chaperones can function in a number of ways. Primarily co-chaperones are involved in the ATPase functionality of their associated heat shock proteins. Co-chaperones catalyze the hydrolysis ATP to ADP on their respective chaperones which then allows them undergo a large conformational change that allows them to either bind to their substrates with higher affinity or aid in the release of the substrate following protein folding, as in the case of co-chaperone p23. J-proteins,

DnaJ In molecular biology, chaperone DnaJ, also known as Hsp40 (heat shock protein 40 kD), is a molecular chaperone protein. It is expressed in a wide variety of organisms from bacteria to humans. Function Molecular chaperones are a diverse family ...

or Hsp40 are important co-chaperones for Hsp70 and have the ability to bind to polypeptides and then recruit chaperone protein DnaK and passes the polypeptide along to this chaperone by catalyzing ATP hydrolysis that allows DnaK to bind to the unfolded polypeptide with high affinity. Another co-chaperone, GrpE, comes in following the folding of this protein to cause a conformational change in DnaK that allows it to release the folded protein. The mechanism of TPR proteins is less studied these domains have been shown to interact with Hsp90 and Hsp70 and may be involved in the creation of an Hsp70-Hsp90 multi-chaperone complex. Co-chaperones may also play an important role in misfolding diseases such as cystic fibrosis. An interaction between Hsp90 and its co-chaperone, Aha1, is essential to the proper folding of cystic fibrosis transmembrane conductance regulator (CFTR). Other examples of co-chaperone's role in illness include neurodegenerative diseases. Alzheimer’s and Parkinson’s disease have a number of proteins that can aggregate if not properly chaperoned. Co-chaperones CSPα (DNAJC5), auxilin (DNAJC6) and RME-8 (DNAJC13) are important for preserving folding and assembly, therefore preventing protein aggregation. Detection of mutations in these proteins have been associated with the early onset of neurodegenerative diseases.

List of co-chaperones

Aha1 Activator of 90 kDa heat shock protein ATPase homolog 1 is an enzyme that in humans is encoded by the ''AHSA1'' gene. Interactions AHSA1 has been shown to interact Advocates for Informed Choice, dba interACT or interACT Advocates for Int ...

* auxilin *

BAG1 BAG family molecular chaperone regulator 1 is a protein that in humans is encoded by the ''BAG1'' gene. Function The oncogene BCL2 is a membrane protein that blocks a step in a pathway leading to apoptosis or programmed cell death. The prote ...

* CAIR-1/Bag-3 *

CDC37 Hsp90 co-chaperone Cdc37 is a protein that in humans is encoded by the ''CDC37'' gene. The protein encoded by this gene is highly similar to Cdc 37, a cell division cycle control protein of Saccharomyces cerevisiae. This protein is a HSP90 Co ...

/p50 * Chp1 * Cysteine string protein (CSP) * Cyp40 * Djp1 *

* E3/E4-

ubiquitin ligase A ubiquitin ligase (also called an E3 ubiquitin ligase) is a protein that recruits an E2 ubiquitin-conjugating enzyme that has been loaded with ubiquitin, recognizes a protein substrate, and assists or directly catalyzes the transfer of ubiquiti ...

* FKBP4 * GAK *

GroES Heat shock 10 kDa protein 1 (Hsp10), also known as chaperonin 10 (cpn10) or early-pregnancy factor (EPF), is a protein that in humans is encoded by the ''HSPE1'' gene. The homolog in '' E. coli'' is GroES that is a chaperonin which usually work ...

GrpE GrpE (''Gro-P'' like protein E) is a bacterial nucleotide exchange factor that is important for regulation of protein folding machinery, as well as the heat shock response. It is a heat-inducible protein and during stress it prevents unfolded prote ...

* Hch1 * Hip (Hsc70-interacting protein)/ST13 * Hop (Hsp70/Hsp90 organizing protein)/STIP1 * Mrj * PP5 * Sacsin * SGT *

Snl1 The first season of ''Saturday Night Live'' (then known as ''NBC's Saturday Night'' to avoid confusion with the similarly named variety show hosted by Howard Cosell), an American sketch comedy series, originally aired in the United States on NBC ...

* SODD/Bag-4 *

Swa2 SWA may refer to: * Eswatini (Swaziland), UNDP-Code * SWA (band), started by Chuck Dukowski * ''SWA'' (magazine), an Indonesian business magazine * SWA, IATA airport code for: ** Shantou Waisha Airport, until 15 December 2011 ** Jieyang Chaoshan In ...

/Aux1 * Tom34 * Tom70 * UNC-45 * WISp39

List of co-chaperones

See also

References

Further reading