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