Transducin

Function

Transducin (TDN) or Heterotrimeric G protein or Guanine nucleotide-binding protein G is a which are organized in two subunits: α and βγ^[1]. TDN is involved in phototransduction. The absorption of a photon by retinal causes a change in the conformation of rhodopsin into metarhodopsin II. The latter causes activation of TDN. Upon TDN activation the is exchanged for the GTP from the cytoplasm. Deactivation of TDN occurs when the GTP bound to the α subunit is hydrolyzed to GDP. Phosducin binds to the βγ subunit of TDN preventing its re-association with the α subunit.

Disease

Congenital stationary night blindness (Nougaret disease) is caused by a mutation in TDN α subunit^[2].

3D structures of transducin

Transducin 3D structures

Structure of rat transducin α (deepskyblue), β (green) and γ (gold) subunits complex with GDP (PDB code 1gp2).

Drag the structure with the mouse to rotate

ReferencesReferences

↑ Lerea CL, Bunt-Milam AH, Hurley JB. Alpha transducin is present in blue-, green-, and red-sensitive cone photoreceptors in the human retina. Neuron. 1989 Sep;3(3):367-76. PMID:2534964
↑ Dryja TP, Hahn LB, Reboul T, Arnaud B. Missense mutation in the gene encoding the alpha subunit of rod transducin in the Nougaret form of congenital stationary night blindness. Nat Genet. 1996 Jul;13(3):358-60. PMID:8673138 doi:http://dx.doi.org/10.1038/ng0796-358

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Michal Harel, Jaime Prilusky, Alexander Berchansky, Joel L. Sussman

[1] Lerea CL, Bunt-Milam AH, Hurley JB. Alpha transducin is present in blue-, green-, and red-sensitive cone photoreceptors in the human retina. Neuron. 1989 Sep;3(3):367-76. PMID:2534964

[2] Dryja TP, Hahn LB, Reboul T, Arnaud B. Missense mutation in the gene encoding the alpha subunit of rod transducin in the Nougaret form of congenital stationary night blindness. Nat Genet. 1996 Jul;13(3):358-60. PMID:8673138 doi:http://dx.doi.org/10.1038/ng0796-358

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