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Rpn3

Rpn3 is a conserved subunit of the 19S regulatory particle of the 26S proteasome found in eukaryotic cells. It is categorized as a non-ATPase component and is encoded by the RPN3 gene in yeast; in humans the functional homolog is PSMD3. As part of the regulatory particle, Rpn3 contributes to the recognition, unfolding, and translocation of ubiquitinated substrates into the core proteolytic chamber.

In terms of function, Rpn3 participates in the assembly and stability of the 19S regulatory particle and

Rpn3 is typically localized to the cytoplasm, where most 26S proteasomes operate, with a distribution that

Evolutionarily, Rpn3 is broadly conserved among eukaryotes, and its yeast and human representatives share functional similarities

See also: 26S proteasome, 19S regulatory particle, proteasome assembly.

plays
a
role
in
substrate
handling
and
gating
of
the
proteasome.
It
interacts
with
multiple
19S
subunits,
including
both
base
and
lid
components,
to
facilitate
efficient
degradation
of
ubiquitinated
proteins.
Disruption
or
malfunction
of
Rpn3
can
compromise
proteasome
activity,
leading
to
the
accumulation
of
damaged
or
misfolded
proteins
and
cellular
stress,
underscoring
its
importance
for
protein
quality
control.
can
extend
to
the
nucleus
in
line
with
nuclear-cytoplasmic
shuttling
of
proteasomes.
Expression
of
Rpn3
is
generally
ubiquitous
across
tissues,
reflecting
the
essential,
housekeeping
role
of
the
proteasome
in
cellular
homeostasis.
as
components
of
the
19S
regulatory
particle.
In
humans,
PSMD3
is
one
of
several
non-ATPase
proteasome
subunits
that
together
regulate
substrate
processing
and
proteasome
dynamics.