Question

What is the role of G-protein in cell communication?

Answer 1

Relay signals from certain cell-surface receptors

Explanation:

G-proteins are coupled to specific cell-surface receptors, the so called 'G-protein coupled receptors' (GPCRs). GPCRs receive signals from outside the cell which are then transferred to the G-protein inside the cell.

G-protein is a 'trimeric GTP-binding protein' attached to the inner (cytoplasmic) face of the cell membrane. It is recruited and activated when a GPCR receives a signal. It uses GTP as an energy source to transfer the signal to its targets.

Targets are either enzymes or ion channels in the plasma membrane that relay the signal onward, thus activating a chain of intracellular signaling proteins. This way several intracellular pathways are activated.