TABLE 1.

Eukaryotic and prokaryotic molecular chaperone and stress protein families

FamilyAlternative name(s)Function
ProkaryotesEukaryotes
ChaperoninsGroEL, GroESHsp60, TriC, CCTFolding of proteins within cage structure
ThioredoxinTrx, DsbA to DsbE, glutaredoxinTrx, glutaredoxin, protein disulfide isomeraseProtein thiol-disulfide exchange
Small HspsIbpA, IbpBHsp25/27, α-crystallinsAdsorption of unfolded chains to prevent stress aggregation
Peptidyl-prolyl isomerasesCyclophilins, FKBPs, parvulinsCyclophilins, FKBPs, parvulinsIsomerization of peptide bond preceding proline
GrpEGrpEGrpEADP/ATP exchange factor interacting with DnaK/DnaJ
Hsp40/DnaJDnaJ, CbpA, RcsGHsp40, Hdj2, Mtj1Hsp70 cochaperones regulating Hsp70 activity
Hsp70DnaK, Hsc66, BiP, mitochondrial Hsp70, etc.Many (e.g., Hsp70, Hsc70)Prevention of aggregation of unfolded protein chains
Hsp90HtpGHsp90, Gp96Regulation of assembly of signal transduction proteins
Hsp100ClpA, ClpB, ClpC, ClpX, ClpYHsp100Disassembly of oligomers and aggregates
Prefoldin nascent chain-associated complexPrefoldinNascent chain-associated complexBinding to nascent chains as they emerge from ribosomes