<prompt> Which of the following statements is true about the G-protein-coupled receptor GPCR?G protein bind the hormones on the surface of the nucleusAll the three subunits a, b and g should bind to each other for G protein to actG protein act as inhibitory and excitatory because of difference in a subunitG protein is bound to GTP in resting state  <response>: G protein can be either stimulatory Gs or inhibitory Gi. Stimulatory or inhibitory activity resides in the a subunit. G-protein coupled receptor GPCR are cell membrane receptors that span the membrane 7 times hennce called seven helix or serpentine receptors. Upon ligand binding to GPCR, a conformational change activates the G protein present inside the cell. Heterotrimeric G protein 3 subunits a,b,g. Couple the cell surface receptor GPCR to catalytic units that catalyse the intracellular formation of second messenger F. In resting-state a subunit is bound to GDP. The intrinsic GTPase activity of the subunit then conves GTP to GDP, and this leads to reassociation of the a with the b-g subunit and termination of effector activation. Ref: Guyton and Hall 13th edition Pgno: 931 