GNB3 Gene: G Protein Subunit Beta 3 - Function, Mutations, and Disease Associations

The GNB3 gene encodes the beta-3 subunit of heterotrimeric G proteins, which are critical components of intracellular signal transduction pathways. G proteins mediate signals from G protein-coupled receptors (GPCRs) to downstream effectors such as adenylyl cyclase and ion channels. The beta-3 subunit forms a dimer with the gamma subunit and modulates receptor coupling and effector activation. A common polymorphism (C825T) in GNB3 is associated with alternative splicing and altered signaling, linked to essential hypertension, obesity, and other cardiovascular and metabolic traits.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• GPCR signaling pathway (Reactome: R-HSA-372790)

• G alpha (i) signaling events (Reactome: R-HSA-418594)

• G alpha (s) signaling events (Reactome: R-HSA-418555)

• Adrenergic signaling in cardiomyocytes (KEGG: hsa04261)

The GNB3 protein (UniProt P16520) is a 340-amino acid beta subunit of heterotrimeric G proteins. It contains seven WD40 repeats that form a beta-propeller structure, mediating interactions with G alpha and G gamma subunits. The protein is ubiquitously expressed with highest levels in adipose tissue, heart, and brain. The C825T polymorphism (rs5443) results in alternative splicing, producing a truncated protein (Gbeta3-s) that exhibits enhanced signaling activity. This gain-of-function variant is associated with essential hypertension, obesity, and related metabolic disorders. GNB3 is not currently a major target in cancer genomics (COSMIC data limited).