symporters

right|thumb|250px|Comparison of Membrane transport protein|transport proteins A symporter is an integral membrane protein that is involved in the transport of two (or more) different molecules across the cell membrane in the same direction. The symporter works in the plasma membrane and molecules are transported across the cell membrane at the same time, and is, therefore, a type of cotransporter. The transporter is called a symporter, because the molecules will travel in the same direction in relation to each other. This is in contrast to the antiport transporter. Typically, the ion(s) will move down the electrochemical gradient, allowing the other molecule(s) to move against the concentration gradient. The movement of the ion(s) across the membrane is facilitated diffusion, and is coupled with the active transport of the molecule(s). In symport, two molecule move in a 'similar direction' at the 'same time'. For example, the movement of glucose along with sodium ions. It exploits the uphill movement of other molecules from low to high concentration, which is against the electrochemical gradient for the transport of solute molecules downhill from higher to lower concentration.

==Examples== thumb|300px|Robert K. Crane and his sketch of the sodium-glucose symporter SGLT1 in the intestinal epithelium transports sodium ions (Na+) and glucose across luminal membrane of the epithelial cells so that it can be absorbed into the bloodstream. This is the basis of oral rehydration therapy. If this symporter did not exist, individual sodium channels and glucose uniporters would not be able to transfer glucose against the concentration gradient and into the bloodstream.