This is Kazutoshi Mori
from Kyoto University.
The title of my talk is the
unfolded protein response.
Protein is a polypeptide when synthesized
according to the central dogma,
and it needs to gain correct tertiary and
quaternary structure to fulfill
its function as assigned
by genetic code.
For example, growth hormone
receptor must have this beautiful
structure to bind to growth hormone.
However, correct folding of proteins
is quite difficult inside the cell,
which contains proteins at
very high concentrations.
So protein folding is
considered to be the last hurdle
for the expression of
such as growth hormone,
and transmembrane proteins,
such as growth hormone receptor,
are folded and assembled in
the endoplasmic reticulum, ER,
the first organelle they
encounter after synthesis
on the membrane-bound ribosome.
The ER contains a number
of molecular chaperones
and folding enzymes abundantly
that assist productive
folding of these proteins, and
only correctly folded molecules
are allowed to move along
the secretory pathway,
and reach their
Because the cell synthesizes a large
number of proteins, some of them,
said to be less than 10%, are
still unfolded or misfolded, even
after the assistance from chaperones.
They are retrotransported
back to the cytosol
to be degraded by the
ubiquitin proteasome system.
This process is called the
ER-associated degradation, ERAD.
Thus, quality control system
operates in the ER.