Beta-gamma complex



(more details...)]]

The beta-gamma complex is composed of the heterotrimeric G proteins Gβ (beta subunit) and Gγ (gamma subunit) that are closely bound to one another.

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.

Function
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.

Genes

 * Gβ genes: GNB1, GNB2, GNB3, GNB4, GNB5,, GNB2L1

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).


 * Gγ genes: GNGT1, GNGT2, GNG2, GNG3, GNG4, GNG5, GNG7, GNG8, GNG10, GNG11, GNG12, GNG13