Chapter 7.3, Problem 1R

Summary Introduction

To review:

The way, by which an activated G protein such as Ras, amplify a response to ligand binding.

Introduction:

G-protein coupled receptor (GPCR) as a signaling pathway is the most common of all. G protein is a lipid-anchoring protein, which is made up of 300 amino acids. It has alpha (α), beta (β), and gamma (γ) subunits, and is heterotrimeric. Gα is linked with guanosine diphosphate (GDP) at one end and to the plasma membrane at another end. It is the largest subunit and has guanosine triphosphatase (GTPase) action. Gβ and Gγ are the other two subunits of G protein.

GPCR signaling pathway has receptor and effector molecules. Effector molecules are generally plasma membrane-bound enzymes like adenylate cyclase and guanylyl cyclase. These effector molecules activate secondary messengers, which in turn, activate the cytosolic enzymes.