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

'G-protein coupled receptors' (GPCRs) are cell-surface receptors to which G-proteins are coupled; GPCRs receive signals from the external environment and forward them to the G-protein within the cell.

Attached to the inner (cytoplasmic) face of the cell membrane, G-protein is a "trimeric GTP-binding protein" that is recruited and activated in response to signals received by GPCRs. It uses GTP as an energy source to transfer signals to its targets.

The signal is transmitted by targets, which are either ion channels or enzymes in the plasma membrane. This initiates a series of intracellular signaling proteins that in turn activate multiple intracellular pathways.

G-proteins play a crucial role in cell communication by carrying signals from the outside to the inside of the cell. They do this by carrying signals from cell surface receptors to intracellular signaling pathways, which in turn trigger different kinds of cell responses.