A heterotrimeric GTP-binding protein that mediates the light activation signal from photolyzed rhodopsin to cyclic GMP phosphodiesterase and is pivotal in the visual excitation process. Activation of rhodopsin on the outer membrane of rod and cone cells causes GTP to bind to transducin followed by dissociation of the alpha subunit-GTP complex from the beta/gamma subunits of transducin. The alpha subunit-GTP complex activates the cyclic GMP phosphodiesterase which catalyzes the hydrolysis of cyclic GMP to 5'-GMP. This leads to closure of the sodium and calcium channels and therefore hyperpolarization of the rod cells.

Annotation

alpha, beta and gamma transducins refer to its subunits

DUI

D015293 MeSH Browser

CUI

M0023545

Previous indexing

Membrane Proteins (1980-1988); Guanine Nucleotide Regulatory Protein (1985-1988)

History note

89

Public note

89