Gt-GTP dissociates to GNAT1-GTP and GNB1:GNGT1

Stable Identifier
R-HSA-2485182
Type
Reaction [dissociation]
Species
Homo sapiens
Compartment
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Binding of transducin (Gt) to activated rhodopsin (MII) promotes the release of GDP from the Gt alpha subunit enabling a GTP (present in a higher concentration than GDP) to take its place. With GTP bound, Gt alpha (GNAT1-GTP) dissociates from the Gt beta:gamma subunits (GNB1:GNGT1) and from MII. MII is then available to bind and activate additional transducins. Transducin activation is the first amplifying step in visual transduction. Many findings came from bovine experiments (Pugh & Lamb 1993, Fung & Stryer 1980, Fung et al. 1981, Hofmann 1985).

Literature References
PubMed ID Title Journal Year
6264430 Flow of information in the light-triggered cyclic nucleotide cascade of vision

Fung, BK, Hurley, JB, Stryer, L

Proc. Natl. Acad. Sci. U.S.A. 1981
8382952 Amplification and kinetics of the activation steps in phototransduction

Pugh, EN, Lamb, TD

Biochim. Biophys. Acta 1993
3933561 Effect of GTP on the rhodopsin-G-protein complex by transient formation of extra metarhodopsin II

Hofmann, KP

Biochim. Biophys. Acta 1985
6930647 Photolyzed rhodopsin catalyzes the exchange of GTP for bound GDP in retinal rod outer segments

Kwok-Keung Fung, B, Stryer, L

Proc. Natl. Acad. Sci. U.S.A. 1980
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