Question

Discuss the differences/similarities between antiporter, uniporter, and symporter carriers. Make sure your explanation discusses gradients of each solute and direction of flow. Be clear how structure allows for the mechanism of transfer. How do changes in structure impact transfer and binding to substrate?

Answer 1

Carrier proteins can be uniporters or co-transporters. Uniporters transport single solute, charged or uncharged, from one side of membrane to the other. The single non coupled transport by uniporter is called uniport. It may use either facilitated diffusion and transport along a diffusion gradient or transport against one with an active transport process.

Co-transporters mediate coupled transport. Coupled transport involves either the simultaneous transfer of a second solute in the same direction, called symport or the transfer of second solute in the opposite direction, called antiport. Co-transporters that mediate symport and antiport are termed symporters and antiporters, respectively.

In symport The movement of the ion/ions across the membrane is facilitated diffusion, and is coupled with the active transport of the molecules.

Antiporters follow secondary active transport in which one species of solute moves along its electrochemical gradient, allowing a different species to move against its own electrochemical gradient.

Figure- three types of carrier mediated transport involving carrier proteins functioning as uniporters, symporters and antiporters.