∞ generated and posted on 2015.12.28 ∞

The pumping of one substance across a membrane as powered by the movement of another substance down its concentration gradient, indeed, down an electrochemical gradient.

Cotransport is membrane transport where the actively transported substance is pumped against its concentration gradient as powered by the movement particularly of an ion, especially H+ or Na+, down its concentration gradient, or rather, down its electrochemical gradient.

Cotransport is also described as secondary active transport because ATP is not used directly to achieve the resulting active transport.

Cotransporters can be differentiated into symporters and antiporters, which are descriptions of the relative direction of the two substances that are being transported, which are same direction and opposite direction, respectively. Similarly, these mechanisms can also be differentiated into cotransport ‐ more strictly defined, i.e., as equivalent to as mediated by a symporter ‐ and countertransport (as mediated by an antiporter).