InnateDB: Systems Biology of the Innate Immune Response

Homo sapiens Protein: GNAT3

Summary

InnateDB Protein

IDBP-233447.5

Last Modified

2014-10-13 [Report errors or provide feedback]

Gene Symbol

GNAT3

Protein Name

guanine nucleotide binding protein, alpha transducing 3

Synonyms

Species

Homo sapiens

Ensembl Protein

ENSP00000381339

InnateDB Gene

IDBG-233445 (GNAT3)

Protein Structure

UniProt Annotation

Function

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. {ECO:0000269PubMed:11917125, ECO:0000269PubMed:17724330}.

Subcellular Localization

Cytoplasm {ECO:0000269PubMed:8015379}. Note=Dual ditribution pattern; plasmalemmal pattern with apical region localization and cytosolic pattern with localization throughout the cytoplasm.

Disease Associations

Tissue Specificity

Expressed in taste buds (sensory organs of clustered epithelial cells) of the circumvallate and foliate papillae of the tongue at protein level. Expressed in enteroendocrine L cells of the gut. Detected also in spermatozoa. {ECO:0000269PubMed:16728727, ECO:0000269PubMed:17021831, ECO:0000269PubMed:17724332, ECO:0000269PubMed:8015379}.

Comments

Interactions

Number of Interactions

This gene and/or its encoded proteins are associated with 4 experimentally validated interaction(s) in this database.

Experimentally validated
Total	4 [view]
Protein-Protein	4 [view]
Protein-DNA	0
Protein-RNA	0
DNA-DNA	0
RNA-RNA	0
DNA-RNA	0

Gene Ontology

Molecular Function

Accession	GO Term
GO:0001664	G-protein coupled receptor binding
GO:0003677	DNA binding
GO:0003924	GTPase activity
GO:0004871	signal transducer activity
GO:0005525	GTP binding
GO:0008020	G-protein coupled photoreceptor activity
GO:0019001	guanyl nucleotide binding
GO:0031683	G-protein beta/gamma-subunit complex binding
GO:0046872	metal ion binding

Biological Process

GO:0001580	detection of chemical stimulus involved in sensory perception of bitter taste
GO:0006184	GTP catabolic process
GO:0007165	signal transduction
GO:0007186	G-protein coupled receptor signaling pathway
GO:0007188	adenylate cyclase-modulating G-protein coupled receptor signaling pathway
GO:0007193	adenylate cyclase-inhibiting G-protein coupled receptor signaling pathway
GO:0007268	synaptic transmission
GO:0007596	blood coagulation
GO:0009584	detection of visible light
GO:0030168	platelet activation
GO:0035094	response to nicotine
GO:0050909	sensory perception of taste
GO:0050913	sensory perception of bitter taste
GO:0050916	sensory perception of sweet taste
GO:0050917	sensory perception of umami taste

Cellular Component

GO:0001669	acrosomal vesicle
GO:0001750	photoreceptor outer segment
GO:0001917	photoreceptor inner segment
GO:0005634	nucleus
GO:0005737	cytoplasm
GO:0005834	heterotrimeric G-protein complex
GO:0005886	plasma membrane
GO:0005930	axoneme
GO:0016324	apical plasma membrane
GO:0043234	protein complex

Protein Structure and Domains

PDB ID

InterPro

IPR001019 Guanine nucleotide binding protein (G-protein), alpha subunit
IPR001408 G-protein alpha subunit, group I
IPR006689 Small GTPase superfamily, ARF/SAR type
IPR011025 G protein alpha subunit, helical insertion
IPR027417 P-loop containing nucleoside triphosphate hydrolase

PFAM

PF00503
PF00025

PRINTS

PR00318
PR00441
PR00328

PIRSF

SMART

SM00275

TIGRFAMs

Post-translational Modifications

Modification

Cross-References

SwissProt