As I was lecturing about membrane transport in my Cell Biology class today, I
realized that I couldn't present a single specific example of primary active
transport (i.e. hydrolyzes ATP) that utilizes a symport mechanism to transport
two substances across a membrane. There are, of course, several examples of
secondary active transport that use gradients of Na+ or H+ to transport other
molecules or ions against their concentration gradient by a symport mechanism.
But are there examples of symports that pump two substances across the
membrane in the same direction using the energy of ATP hydrolysis? I can't
think of any. Might some of the ABC transporters fall into this category?
As for antiporters involved in primary active transport, the only one I know
about is the Na+/K+ ATPase. Are there others?
Thanks in advance for your help.
Brian T. Greuel
Dept. of Biology
University of Scranton
Scranton, PA 18510-4625
email: greuelb1 at uofs.edu
