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GAL4

GAL4 is a transcription activator protein in the yeast Saccharomyces cerevisiae that regulates the GAL gene regulon, enabling the utilization of galactose as a carbon source. Gal4p binds to upstream activating sequences (UAS_GAL) located near GAL genes such as GAL1, GAL7, and GAL10, and promotes transcription when galactose is available.

Regulation of Gal4p activity is part of the GAL regulon. In the absence of galactose, GAL80 binds

Gal4p has a DNA-binding domain of the Zn2Cys6 binuclear cluster family at the N-terminus and a C-terminal

Beyond yeast biology, the GAL4-UAS system has become a widely used binary expression system in genetic research.

See also: GAL regulon, Zn2Cys6 transcription factors, GAL4-UAS system.

to
Gal4p
and
inhibits
its
transcriptional
activation
domain.
When
galactose
is
present,
GAL3
senses
the
signal
and,
with
ATP,
binds
GAL80,
relieving
inhibition
and
allowing
Gal4p
to
recruit
RNA
polymerase
II
and
coactivators
to
drive
transcription.
activation
domain.
Binding
to
UAS_GAL
enables
assembly
of
the
transcriptional
machinery
and
chromatin
remodeling,
leading
to
expression
of
GAL
enzymes
such
as
galactokinase
(GAL1),
galactose-1-phosphate
uridylyltransferase
(GAL7),
and
UDP-glucose
4-epimerase
(GAL10).
A
GAL4
driver
(expressed
in
a
specific
tissue
or
condition)
activates
transcription
of
a
gene
placed
downstream
of
UAS
sequences
in
responder
constructs.
The
method
has
been
deployed
in
Drosophila
and
other
organisms
to
achieve
controlled
gene
expression.