G beta-gamma complex
Heterotrimeric G protein complexes ( Gαβγ) are formed from Gα, Gβ, and Gγ subunits. Upon activation of a G-protein coupled receptor, the Gβγ complex is released from the Gα subunit, allowing the Gα subunit to function as a messenger in signal transduction.
The normal role of the beta-gamma complex is inhibition of the Gα subunit. However, the free Gβγ complex can act as a signaling molecule itself, by activating other second messengers or by gating ion channels directly.
Examples of Gβγ complex functions include:
- Activation of phospholipase A2 when bound to histamine receptors
- Direct opening of G-protein coupled inward rectifying potassium channels (GIRKs) when bound to muscarinic acetylcholine receptors
- Activation L-type calcium channels, as in H3 receptor pharmacology.
- Initiation of the phospholipase C pathway by activating phospholipase C, as a minor mechanism of growth hormone releasing hormone releasing growth hormone.
GNB1L and GNB2L1 are not considered to be classical G protein beta subunits, as they do not make part of the beta/gamma protein complex and only show sequence similarities with the true Gβ proteins (ref NCBI GeneID: 54584, GeneID: 10399).
- GeneGlobe -> GHRH Signaling Retrieved on May 31, 2009