gonadotropin-releasing hormone and adipokinetic hormone receptors, member of the class A family of seven-transmembrane G protein-coupled receptors
Gonadotropin-releasing hormone (GnRH) and adipokinetic hormone (AKH) receptors share strong sequence homology to each other, suggesting that they have a common evolutionary origin. GnRHR, also known as luteinizing hormone releasing hormone receptor (LHRHR), plays an central role in vertebrate reproductive function; its activation by binding to GnRH leads to the release of follicle stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland. Adipokinetic hormone (AKH) is a lipid-mobilizing hormone that is involved in control of insect metabolism. Generally, AKH behaves as a typical stress hormone by mobilizing lipids, carbohydrates and/or certain amino acids such as proline. Thus, it utilizes the body's energy reserves to fight the immediate stress problems and subdue processes that are less important. Although AKH is known to responsible for regulating the energy metabolism during insect flying, it is also found in insects that have lost its functional wings and predominantly walk for their locomotion. Both GnRH and AKH receptors are members of the class A of the seven-transmembrane, G-protein coupled receptor (GPCR) superfamily.