Definitions of G Protein alpha Subunit
GTP- BINDING PROTEINS that contain three non- identical subunits. They are found associated with members of the seven transmembrane domain superfamily of G- protein coupled receptors. The G- alpha subunit acts as a signal transduction molecule when it binds GTP and dissociates from the heterotrimer. Hydrolysis of GTP by the inherent GTPase activity of the protein causes it to revert to its inactive ( heterotrimeric) form. EC 3. 6. 1.-.