A secondary active transport mechanism modelling

A sustained effort in biochemical, biophysical and physiological research is devoted to the characterization of the transfer of ions and molecules between biological membranes and their aqueous environment. The transported molecules include compounds with substantial structural and physico-chemical differences. It is widely assumed that the biological activity of these compounds arises as a result of binding to active sites in membrane-bound proteins, while the lipid background is considered to play a more passive role. In the simple, symmetric, four-state carrier model for transport of a single solute, transport is down the concentration gradient of that solute. However, a simple modification of this model results in transport up the solute concentration gradient.