CAD
Protein
-
PALA
Resistance -
CAD
protein
is
a
multifunctional
enzyme.
It
catalyzes
the,
first
three
reactions
of
endogenous
uridine
synthesis,
one
of
which
is
inhibited
by
PALA
(N-phosphonacetyl-L-aspartate).
Mammalian
cells
are
sensitive
to
PALA.
PALA-resistant
cell
lines
developed
through
selection
overproduce
CAD
protein
due
to
a
high
amplification
of
the
concerned
gene.
CAD
gene
isolated
from
Syrian
hamster
serves
as
a
dominant
marker
making
normal
mammalian
cells
resistant
to
high
concentrations
of
P
ALA.
This
gene,
like
the
DHFR
gene,
becomes
highly
amplified
in
the
stably
transfected
cell
lines.
