G protein subunit alpha transducin 2
Last updated 11 Aug 2025
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The GNAT2 gene provides instructions for making one part (called the cone-specific alpha subunit) of a protein called transducin. This protein is found in light-detecting (photoreceptor) cells called cones, which are located in a specialized tissue at the back of the eye known as the retina. Cones provide vision in bright light (daylight vision), including colour vision. Other photoreceptor cells, called rods, provide vision in low light (night vision).
Normal function
The GNAT2 gene provides instructions for making one part (called the cone-specific alpha subunit) of a protein called transducin. This protein is found in light-detecting (photoreceptor) cells called cones, which are located in a specialized tissue at the back of the eye known as the retina. Cones provide vision in bright light (daylight vision), including colour vision. Other photoreceptor cells, called rods, provide vision in low light (night vision).
Transducin plays an essential role in transmitting visual signals from photoreceptor cells in the retina to the brain through a process called phototransduction. Photoreceptors contain special pigments (called photopigments) that absorb light. The photopigments activate transducin, which triggers a series of chemical reactions within the cell. These reactions alter the cell's electrical charge, ultimately generating a signal that is interpreted by the brain as vision.
Conditions referring to this gene or chromosome
Other names
ACHM4
cone-type transducin alpha subunit
GNAT2_HUMAN
GNATC
guanine nucleotide binding protein (G protein), alpha transducing activity polypeptide 2
guanine nucleotide binding protein, alpha transducing activity polypeptide 2
transducin alpha-2 chain
transducin, cone-specific, alpha polypeptide
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Further reading and references
- G protein subunit alpha transducin 2; MedlinePlus, National Library of Medicine.
- Aligianis IA, Forshew T, Johnson S, Michaelides M, Johnson CA, Trembath RC, Hunt DM, Moore AT, Maher ER. Mapping of a novel locus for achromatopsia (ACHM4) to 1p and identification of a germline mutation in the alpha subunit of cone transducin (GNAT2). J Med Genet. 2002 Sep;39(9):656-60. doi: 10.1136/jmg.39.9.656.
- Kohl S, Baumann B, Rosenberg T, Kellner U, Lorenz B, Vadala M, Jacobson SG, Wissinger B. Mutations in the cone photoreceptor G-protein alpha-subunit gene GNAT2 in patients with achromatopsia. Am J Hum Genet. 2002 Aug;71(2):422-5. doi: 10.1086/341835. Epub 2002 Jun 20.
- Kohl S, Jagle H, Wissinger B, Zobor D. Achromatopsia. 2004 Jun 24 [updated 2018 Sep 20]. In: Adam MP, Bick S, Mirzaa GM, Wallace SE, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2026. Available from http://www.ncbi.nlm.nih.gov/books/NBK1418/
- Michaelides M, Aligianis IA, Holder GE, Simunovic M, Mollon JD, Maher ER, Hunt DM, Moore AT. Cone dystrophy phenotype associated with a frameshift mutation (M280fsX291) in the alpha-subunit of cone specific transducin (GNAT2). Br J Ophthalmol. 2003 Nov;87(11):1317-20. doi: 10.1136/bjo.87.11.1317.
- Ouechtati F, Merdassi A, Bouyacoub Y, Largueche L, Derouiche K, Ouragini H, Nouira S, Tiab L, Baklouti K, Rebai A, Schorderet DF, Munier FL, Zografos L, Abdelhak S, El Matri L. Clinical and genetic investigation of a large Tunisian family with complete achromatopsia: identification of a new nonsense mutation in GNAT2 gene. J Hum Genet. 2011 Jan;56(1):22-8. doi: 10.1038/jhg.2010.128. Epub 2010 Nov 25.
- Pina AL, Baumert U, Loyer M, Koenekoop RK. A three base pair deletion encoding the amino acid (lysine-270) in the alpha-cone transducin gene. Mol Vis. 2004 Apr 8;10:265-71.
- Rosenberg T, Baumann B, Kohl S, Zrenner E, Jorgensen AL, Wissinger B. Variant phenotypes of incomplete achromatopsia in two cousins with GNAT2 gene mutations. Invest Ophthalmol Vis Sci. 2004 Dec;45(12):4256-62. doi: 10.1167/iovs.04-0317.
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