G protein

G PROTEIN The sequence of events that occur to bring about a cellular response following activation of a G-protein coupled receptorG protein coupled receptors are found in choanoflagellates and yeast. The ligands that tie and energize these receptors incorporate hormones, light sensitive compounds, neurotransmitters, and odors. G-protein-coupled receptors are a group of plasma membrane receptors such as helix receptors and serpentine receptors. G proteins are the guanine nucleotide joining proteins that function as intermediaries in signal pathways. There are two significant signal activation pathways incorporating the G protein coupled receptors; the phosphatidylinositol signal course and the Camp signal course (Miller & Newton, 2010 p. 260).
The biological signals send by the G proteins are received by the receptors. In addition, the G proteins forward the signals by a way of mediation of various numbers of intermediaries to those effectors that control genes in reaction to the signals. Following activation of the G protein coupled receptors, the ligand attach to the G protein coupled receptors which causes a conformational transformation in the G protein coupled receptors thus permitting it to function as guanine nucleotide exchange element (Miller & Newton, 2010 p. 268).
When the G protein coupled receptors are activated, the GEF sphere activate or energizes the G protein by aiding in the exchange of GTP. As such, the G proteins subunits delink from the main receptor in order to produce a Gβγ dimer and Gα-GTP monomer, which are permitted to regulate the function of other cellular and intracellular proteins.
Reference
Millar, R. P., & Newton, C. L, 2010, The year in G protein-coupled receptor research. Mol. Endocrinol. 24 (1): 261–74.