Question

What are uni-, sym- and antiporter pumps?

Answer 1

Uniport is the membrane transport through facilitated diffusion. Uniport is transmembrane protein that transports the ions in a single direction. Uniporters act as primary active transport and are carrier proteins that bind to a single substrate and transport across the concentration gradient. Voltage-gated sodium channels and calcium transport into the presynaptic neuron by voltage-gated calcium channels are examples of uniport.

Symport is also known as co-transport in which the solute and Na⁺ ions are passed through the membrane in the same direction mostly into the cell. For example, glucose and amino acids transported via symport in intestinal and kidney cells.

Antiport is also known as counter transport or exchange in which the solute and the Na⁺ ions pass through the membrane in opposite directions i.e, the ions into the cell and solute out of the cell. For example, exchange of Na⁺ and H⁺ ions in a cell occurs by means of antiport. The (Na⁺ - K⁺) - ATPase works as an antiport generating the charge separation across the membrane. The mechanism proceeds by the exchange of three positive charges out of the cell for every two positive charges that enter the cell.