Ghrelin O-acyltransferase also known as membrane bound O-acyltransferase domain containing 4 is an enzyme that in humans is encoded by the MBOAT4 gene.
It is homologous to other membrane-bound O-acyltransferases. It is a polytopic membrane protein what takes part in lipid signaling reactions. It is the only known enzyme that catalyzes the acylation of ghrelin through the transfer of n-octanoic acid to ghrelin Ser3. Ghrelin O-acyltransferase function is essential in regulation of appetite and the release of growth hormone. Ghrelin O-acyltransferase is a target for scientific research due to promising applications in the treatment of diabetes, eating disorders, and metabolic diseases.
Consistent with its function relative to ghrelin, ghrelin O-acyltransferase can be found in all vertebrates, including mammals, birds, and fish species, apart from some reptiles. The enzyme is primarily expressed in the stomach and the gastrointestinal system. Other sites where ghrelin O-acyltransferase can be found include tissue from the brain, the pancreas, the pituitary gland, and certain forms of cancer.