There is good evidence that cotransporters of the symport type behave as molecular water pumps, in which a water flux is coupled to the substrate fluxes. The free energy stored in the substrate gradients is utilized, by a mechanism within the protein, for the transport of water.

What is the function of protein pumps?

Pumps, also called transporters, are transmembrane proteins that actively move ions and/or solutes against a concentration or electrochemical gradient across biological membranes. Pumps generate a membrane potential by creating an electrochemical gradient across the membrane.

What is a molecular pump in biology?

: a vacuum pump that depends for its action on the adhesion of the gas or vapor molecules to a rapidly moving metal disk or cylinder by which they are carried away.