The heterotrimeric guanine nucleotide-binding proteins (G proteins) are signal transducers that communicate signals from many hormones, neurotransmitters, chemokines, and autocrine and paracrine factors.

The extracellular signals are received by members of a large superfamily of receptors with seven membrane-spanning regions that activate the G proteins, which route the signals to several distinct intracellular signaling pathways.

These pathways interact with one another to form a network that regulates metabolic enzymes, ion channels, transporters, and other components of the cellular machinery controlling a broad range of cellular processes, including transcription, motility, contractility, and secretion.

These cellular processes in turn regulate systemic functions such as embryonic development, gonadal development, learning and memory, and organismal homeostasis. Heterotrimeric G proteins play vital roles in cellular responses to external signals. The specificity of a G protein-receptor interaction is primarily mediated by the gamma subunit.

Guanine nucleotide-binding proteins (G proteins) transduce extracellular signals received by transmembrane receptors to effector proteins.

Members (subunits)

 alpha subunits

GNAS1	GNA1	GNA2	GNA3	GNA4	GNA5	GNA6	GNA7
GNA8	GNA9	GNA10	GNA11	GNA12	GNA13	GNA14	GNA15

 beta subunits

GNB1

GNB2

 gamma subunits

GNG1	GNG2	GNG3	GNG4	GNG5	GNG6	GNG7
GNG8	GNG9	GNG10	GNG11	GNG12	GNG13

Pathology

 mutations of GNAS1

GNAS1	Albright hereditary osteodystrophy
GNAS1	pseudohypoparathyroidism type Ia (PHP Ia)
GNAS1	pseudopseudohypoparathyroidism (PPHP)
GNAS1	pituitary tumors

References

 Bellaiche Y, Gotta M. Heterotrimeric G proteins and regulation of size asymmetry during cell division. Curr Opin Cell Biol. 2005 Dec;17(6):658-63. PMID: #16243504#

 Robishaw JD, Berlot CH. Translating G protein subunit diversity into functional specificity. Curr Opin Cell Biol. 2004 Apr;16(2):206-9. PMID: #15196565#

 Neves SR, Ram PT, Iyengar R. G protein pathways. Science. 2002 May 31;296(5573):1636-9. PMID: #12040175#

 Farfel Z, Bourne HR, Iiri T. The expanding spectrum of G protein diseases. N Engl J Med. 1999 Apr 1;340(13):1012-20. PMID: #10099144#