Ghrelin is the ligand for growth hormone secretagogue receptor type 1 (GHSR). Induces the release of growth hormone from the pituitary. Has an appetite-stimulating effect, induces adiposity and stimulates gastric acid secretion. Involved in growth regulation (By similarity). Obestatin may be the ligand for GPR39. May have an appetite-reducing effect resulting in decreased food intake. May reduce gastric emptying activity and jejunal motility (By similarity). 2.5-fold increase in plasma level of ghrelin upon fasting. O-octanoylated by GOAT/MBOAT4 (By similarity). O-octanoylation or O-decanoylation is essential for ghrelin activity. The O-decanoylated forms Ghrelin-27-C10 and Ghrelin-28-C10 differ in the length of the carbon backbone of the carboxylic acid bound to Ser-26. A small fraction of ghrelin, ghrelin-27-C10:1, ghrelin-27-C10:2, ghrelin-28-C8:1, ghrelin-28-C10:1, and ghrelin-28-C10:2, may be modified with singly or doubly unsaturated carboxylic acids (PubMed:16466902). Amidation of Leu-98 is essential for obestatin activity. Ghrelin-28-C10, O-decanoylated form. Ghrelin-28-C10:1, O-decenoylated form. Ghrelin-28-C10:2, O-decadienoylated form. Ghrelin-28-C8, O-octanoylated form. Ghrelin-28-C1, O-octenoylated form. des-Gln14-Ghrelin-28-C8, O-octanoylated form. Ghrelin-27-C10, O-decanoylated form. Ghrelin-27-C10:1, O-decenoylated form. Ghrelin-27-C10:2, O-decadienoylated form. Ghrelin-27-C8, O-octanoylated form. des-Gln14-Ghrelin-27-C8, O-octanoylated form. Belongs to the motilin family. Gut feelings - Issue 66 of January 2006