G Protein Activation/Inactivation Cycle and Nitric Oxide Action

G Protein Activation/Inactivation Cycle

-G-Protein linked receptors contain seven transmembrane segments that form a ligand-binding site on the inside.

(1) Ligand binds to receptor

(2) Receptor activates a G protein by causing the Alpha subunit to release GDP and aquire GTP

(3) The Alpha and Beta-Gamma complex subunits then seperate 

(4) This initiates signal transduction events e.g. G protein subunits activate or inhibit target proteins 

(5) The GTP Alpha subunit eventually hydrolyses its bound GTP converting the subunit…