CPLM-024566

Genbank Nucleotide ID

Guanine nucleotide-binding protein G(t) subunit alpha-3

Protein Synonyms/Alias

Gustducin alpha-3 chain

Homo sapiens (Human)

Position	Peptide	Type	References
51	SGKSTIVKQMKIIHK	ubiquitination	[1, 2, 3, 4]

[1] Systematic and quantitative assessment of the ubiquitin-modified proteome.
Kim W, Bennett EJ, Huttlin EL, Guo A, Li J, Possemato A, Sowa ME, Rad R, Rush J, Comb MJ, Harper JW, Gygi SP.
Mol Cell. 2011 Oct 21;44(2):325-40. [PMID: 21906983]
[2] Global identification of modular cullin-RING ligase substrates.
Emanuele MJ, Elia AE, Xu Q, Thoma CR, Izhar L, Leng Y, Guo A, Chen YN, Rush J, Hsu PW, Yen HC, Elledge SJ.
Cell. 2011 Oct 14;147(2):459-74. [PMID: 21963094]
[3] Refined preparation and use of anti-diglycine remnant (K-ε-GG) antibody enables routine quantification of 10,000s of ubiquitination sites in single proteomics experiments.
Udeshi ND, Svinkina T, Mertins P, Kuhn E, Mani DR, Qiao JW, Carr SA.
Mol Cell Proteomics. 2013 Mar;12(3):825-31. [PMID: 23266961]
[4] Integrated proteomic analysis of post-translational modifications by serial enrichment.
Mertins P, Qiao JW, Patel J, Udeshi ND, Clauser KR, Mani DR, Burgess MW, Gillette MA, Jaffe JD, Carr SA.
Nat Methods. 2013 Jul;10(7):634-7. [PMID: 23749302]

Functional Description

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.

NP_BIND 40 47 GTP (By similarity).
NP_BIND 175 181 GTP (By similarity).
NP_BIND 200 204 GTP (By similarity).
NP_BIND 269 272 GTP (By similarity).
METAL 47 47 Magnesium (By similarity).
METAL 181 181 Magnesium (By similarity).
BINDING 326 326 GTP; via amide nitrogen (By similarity).
LIPID 2 2 N-myristoyl glycine (By similarity).

Complete proteome; Cytoplasm; GTP-binding; Lipoprotein; Magnesium; Metal-binding; Myristate; Nucleotide-binding; Reference proteome; Transducer.

UniProt (SWISSPROT/TrEMBL); GenBank; EMBL

GO:0016324; C:apical plasma membrane; IEA:Compara.
GO:0005737; C:cytoplasm; IEA:UniProtKB-SubCell.
GO:0005834; C:heterotrimeric G-protein complex; IBA:RefGenome.
GO:0001917; C:photoreceptor inner segment; IBA:RefGenome.
GO:0001750; C:photoreceptor outer segment; IBA:RefGenome.
GO:0031683; F:G-protein beta/gamma-subunit complex binding; IBA:RefGenome.
GO:0001664; F:G-protein coupled receptor binding; IBA:RefGenome.
GO:0005525; F:GTP binding; IEA:UniProtKB-KW.
GO:0003924; F:GTPase activity; IBA:RefGenome.
GO:0046872; F:metal ion binding; IEA:UniProtKB-KW.
GO:0004871; F:signal transducer activity; IBA:RefGenome.
GO:0007188; P:adenylate cyclase-modulating G-protein coupled receptor signaling pathway; IBA:RefGenome.
GO:0001580; P:detection of chemical stimulus involved in sensory perception of bitter taste; IBA:RefGenome.
GO:0035094; P:response to nicotine; IEA:Compara.
GO:0050916; P:sensory perception of sweet taste; IBA:RefGenome.
GO:0050917; P:sensory perception of umami taste; IBA:RefGenome.

IPR001408; Gprotein_alpha_I.
IPR001019; Gprotein_alpha_su.
IPR011025; GproteinA_insert.
IPR027417; P-loop_NTPase.

PR00318; GPROTEINA.
PR00441; GPROTEINAI.