Chaperones, Molecular
495
Tab. 1
Selected examples of the majorchaperone families in the cell.
Name
of
family
Prokaryotic
examples
Eukaryotic
examples
Cellular
location
Known
cochaperones
Cellular functions
Hsp60
GroEL
Cytosol
GroES
Folding of a subset of newly synthesized proteins,
folding of a subset of proteins damaged by heat
shock and other stresses
CCT (archaea)
Cytosol
GimC
Unknown; induced by heat shock
Hsp60
Mitochondria
Hsp10
Import of proteins synthesized in cytosol, folding of
proteins, protection against heat shock
RuBP (rubisco
subunit
binding
protein)
Chloroplasts
Cpn21
Import and folding of proteins synthesized in cytosol,
and folding of proteins synthesized within
chloroplasts, particularly the large subunit of
rubisco
CCT
Cytosol
GimC
Folding of actin and tubulin, folding of other cytosolic
proteins
Hsp70 with Hsp40
DnaK/DnaJ
Cytosol
GrpE
Binding to nascent polypeptides, protection of protein
from aggregation at high temperatures, dissolution
of aggregates (with ClpB), regulation of heat shock
response in
E. coli
Hsp70/Hsp40
Cytosol
Fes1, Bag1
Multiple proteins and multiple roles including binding
of nascent proteins, protein import into organelles,
uncoating of clathrin cages
BiP/Sec63
ER
SLS1, BAP
Binding of incompletely folded secretory proteins,
facilitating retrotranslocation to cytosol for
proteasome degradation; note: several different
proteins with J-domains interact with BiP
mtHsp70/Mdj1
Mitochondria
Mt-GrpE
Import andfolding of proteins, heat shock protection
(
continued overleaf
)
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