Hello, my name is Michel Leroux,
I'm an associate professor in
the Molecular Biology and Biochemistry
Department at Simon Fraser University.
Today I'd like to talk to you about
the role of chaperonin-like proteins in
Chaperonins belong to a family of
proteins termed 'molecular chaperones',
these play various important
roles in protein quality control.
There are many types of chaperones,
here I list three major classes:
there is the Hsp70 class,
the Hsp60 class (which are also termed
chaperonins), as well as Hsp90.
Together these play important functions in
the cell including folding of proteins,
assembly of oligomeric complexes, and
targeting of proteins to different
They also play roles in protein
dis-aggregation and protein degradation.
In the context of de novo protein folding,
Hsp70 and chaperonins play critical roles.
As seen in the bottom part of the slide,
Hsp70 helps to stabilize polypeptide
chains that emerge from the ribosome,
whereas chaperonins are thought to mainly
assist in post-translational folding
of the newly-made polypeptides.
There are two groups of chaperonins,
group I chaperonins are represented
by GroEL, which is found in bacteria.
Other group I chaperonins include
mitochondrial Hsp60 (mtHsp60) and
chloroplast Hsp60 (cpHsp60).
Group II chaperonins, on the other hand,
are present in the eukaryotic and
In eukaryotes the main
chaperonin is called CCT, or
chaperonin containing TCP-1, it is also
called TRiC or TCP-1 ring complex.
In archaea the cytosolic chaperonin is
usually referred to as 'thermosome'
because it's particularly abundant
under heat shock conditions.