Question

What other factors limit or terminatesignalling via GPCRs?

Short answer

The GPCRs are transmembrane proteins that bind their corresponding agonist (such as a hormone) on their extracellular side, changing its conformation on the cytoplasmic side in the process. When a GPCR connects to its corresponding agonist, heterotrimeric G proteins that are attached to the cytoplasmic side of the plasma membrane are activated.

Step-by-step solution

Essential sensory function.

The GPCRs form one of the largest known protein families. In addition, GPCRs have essential sensory functions.

GPCR cell-surface protein.

G-protein–coupled receptor, is a cell-surface protein with seventransmembrane helices that interact with an associated G protein onligand binding. In many cases, this also increases the affinity of the GPCR for its agonist.

GPCR allosteric proteins.

GPCRs operate similarly to allosteric proteins like haemoglobin.The receptor can send an extracellular signal to the interior of the cell by switching between two distinct conformations, one with the agonist attached and one without.For GPCRs, this conformational shift is transmitted to the cytoplasmic face of the receptor by its transmembrane helices, allowing the appropriate heterotrimeric G protein to attach.