Aliases for GNAT3 Gene
External Ids for GNAT3 Gene
Previous GeneCards Identifiers for GNAT3 Gene
Sweet, bitter, and umami tastes are transmitted from taste receptors by a specific guanine nucleotide binding protein. The protein encoded by this gene is the alpha subunit of this heterotrimeric G protein, which is found not only in the oral epithelium but also in gut tissues. Variations in this gene have been linked to metabolic syndrome. [provided by RefSeq, Dec 2015]
GeneCards Summary for GNAT3 Gene
GNAT3 (G Protein Subunit Alpha Transducin 3) is a Protein Coding gene. Among its related pathways are Carbohydrate digestion and absorption and Taste transduction. GO annotations related to this gene include GTP binding and signal transducer activity. An important paralog of this gene is GNAQ.
UniProtKB/Swiss-Prot for GNAT3 Gene
Guanine nucleotide-binding protein (G protein) alpha subunit playing a prominent role in bitter and sweet taste transduction as well as in umami (monosodium glutamate, monopotassium glutamate, and inosine monophosphate) taste transduction. Transduction by this alpha subunit involves coupling of specific cell-surface receptors with a cGMP-phosphodiesterase; Activation of phosphodiesterase lowers intracellular levels of cAMP and cGMP which may open a cyclic nucleotide-suppressible cation channel leading to influx of calcium, ultimately leading to release of neurotransmitter. Indeed, denatonium and strychnine induce transient reduction in cAMP and cGMP in taste tissue, whereas this decrease is inhibited by GNAT3 antibody. Gustducin heterotrimer transduces response to bitter and sweet compounds via regulation of phosphodiesterase for alpha subunit, as well as via activation of phospholipase C for beta and gamma subunits, with ultimate increase inositol trisphosphate and increase of intracellular Calcium. GNAT3 can functionally couple to taste receptors to transmit intracellular signal: receptor heterodimer TAS1R2/TAS1R3 senses sweetness and TAS1R1/TAS1R3 transduces umami taste, whereas the T2R family GPCRs act as bitter sensors. Functions also as lumenal sugar sensors in the gut to control the expression of the Na+-glucose transporter SGLT1 in response to dietaty sugar, as well as the secretion of Glucagon-like peptide-1, GLP-1 and glucose-dependent insulinotropic polypeptide, GIP. Thus, may modulate the gut capacity to absorb sugars, with implications in malabsorption syndromes and diet-related disorders including diabetes and obesity.
Heterotrimeric G proteins are membrane bound GTPases that are linked to 7-TM receptors. Each G protein contains an alpha-, beta- and gamma-subunit and is bound to GDP in the 'off' state. Ligand binding causes a receptor conformational change, detaching the G protein and switching it 'on'.