Gustducin

guanine nucleotide binding protein, alpha transducing 3
Identifiers
Symbol	GNAT3
Entrez	346562
HUGO	22800
OMIM	139395
RefSeq	XM_294370
UniProt	A4D1B2
Other data
Locus	Chr. 7 q21.11

guanine nucleotide binding protein (G protein), beta polypeptide 1
Identifiers
Symbol	GNB1
Entrez	2782
HUGO	4396
OMIM	139380
RefSeq	NM_002074
UniProt	P62873
Other data
Locus	Chr. 1 p36.33

guanine nucleotide binding protein (G protein), gamma 13
Identifiers
Symbol	GNG13
Entrez	51764
HUGO	14131
OMIM	607298
RefSeq	NM_016541
UniProt	Q9P2W3
Other data
Locus	Chr. 16 p13.3

Gustducin is a G protein associated with taste and the gustatory system, found in some taste receptor cells. Research on the discovery and isolation of gustaducin is recent. It is known to play a large role in the transduction of bitter, sweet and umami stimuli. Its pathways (especially for detecting bitter stimuli) are many and diverse.

An intriguing feature of gustducin is its similarity to transducin. These two G proteins have been shown to be structurally and functionally similar, leading researchers to believe that the sense of taste evolved in a similar fashion to the sense of sight.

Gustducin is a heterotrimeric protein composed of the products of the GNAT3 (α-subunit), GNB1 (β-subunit) and GNG13 (γ-subunit).

Gustducin was discovered in 1992 when degenerate oligonucleotide primers were synthesized and mixed with a taste tissue cDNA library. The DNA products were amplified by the polymerase chain reaction method, and eight positive clones were shown to encode the α subunits of G-proteins, (which interact with G-protein-coupled receptors). Of these eight, two had previously been shown to encode rod and cone α-transducin. The eighth clone, α-gustducin, was unique to the gustatory tissue.

Upon analyzing the amino-acid sequence of α-gustducin, it was discovered that α-gustducins and α-transducins were closely related. This work showed that α-gustducin's protein sequence gives it 80% identity to both rod and cone a-transducin. Despite the structural similarities, the two proteins have very different functionalities.

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Wikipedia