Membrane transport question

Brian T. Greuel greuelb1 at
Wed Sep 25 11:17:29 EST 1996

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

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