E.Coli
Dicarboxylic
Acid
System
This system transports succinate, malate and fumarate, and is energized by a proton gradient. It appears to be dependent on the products of three different genes.
One of the genes codes a protein that binds lactate in addition to succinate, malate and fumarate. The proteins of the other two genes bind succinate, malate and fumarate, but not lactate.
The
two
proteins
are
located
close
to
each
other
and
appear
to
span
the
membrane.It
will
thus
be
seen
that
the
dicarboxylic
acid
system
has
two
membrane
proteins,
while
the
lactose
premease
system
has
only
one
