Question

Summarize and explain the mechanism of (1)ATP-powered pump, (2)ion channel and (3)transporter including uniporter, symporter and antiporter

Answer 1

ATP-powered pumps (ATPases) couple the splitting, or hydrolysis, of ATP with the movement of ions across a membrane against a concentration gradient. ATP is hydrolyzed directly to ADP and inorganic phosphate, and the energy released is used to move one or more ions across the cell membrane.

Ion channels catalyze the diffusion of inorganic ions down their electrochemical gradients across cell membranes. Because the ionic movements are passive, ion channels would seem to be extraordinarily simple physical systems, yet they are responsible for electrical signalling in living cells.

A uniporter is an integral membrane protein that transports a single type of substrate species (charged or uncharged) across a cell membrane. It may use either facilitated diffusion and transport along a diffusion gradient or transport against one with an active transport process.

A symporter is an integral membrane protein that is involved in the transport of many different types of molecules across the cell membrane. 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.

An antiporter is a cotransporter and integral membrane protein involved in the secondary active transport of two or more different molecules or ions across a phospholipid membrane such as the plasma membrane in opposite directions, one into the cell and one out of the cell.