G proteins are composed of 3 units, alpha, beta and gamma and are involved in the modulation and transduction of various transmembrane signalling systems. There are families of related genes for each subunit. GNB3 encodes a beta subunit. Beta subunits are required for GTPase activity, for replacement of GDP by GTP, regulate alpha subunits and for G protein-effector interactions. A single-nucleotide polymorphism (C825T) in this gene is associated with essential hypertension and obesity ａnd