title: Enzymatic characterization of GOAT, ghrelin O-acyltransferase.
abstract: Ghrelin is a gastric peptide hormone in which serine 3 (threonine 3 in frogs) is modified primarily by an n-octanoic acid; this modification is essential for ghrelin's activity. The enzyme that transfers n-octanoic acid to the third serine residue of ghrelin peptide has been identified and named GOAT for ghrelin O-acyltransferase. GOAT is the only known enzyme that catalyzes the acyl modification of ghrelin and specifically modifies the third amino acid serine and does not modify other serine residues in ghrelin peptides. GOAT prefers n-hexanoyl-CoA over n-octanoyl-CoA as the acyl donor, although in the stomach n-octanoyl form is the main acyl-modified ghrelin and the concentration of n-hexanoyl form is very low. Moreover, a four-amino acid peptide derived from the N-terminal sequence of ghrelin can be modified by GOAT, indicating that these four amino acids constitute the core motif for substrate recognition by the enzyme.
authors.affiliation: Molecular Genetics, Institute of Life Science, Kurume University, Kurume, Fukuoka, Japan.
authors.forename: Hideko
authors.initials: H
authors.lastname: Ohgusu
authors.forename: Tomoko
authors.initials: T
authors.lastname: Takahashi
authors.forename: Masayasu
authors.initials: M
authors.lastname: Kojima
mesh_terms: D000215:Acylation; D000217:Acyltransferases / Q000737:chemistry* / Q000235:genetics; D000818:Animals; D016466:CHO Cells; D002210:Caprylates / Q000737:chemistry; D002462:Cell Membrane / Q000737:chemistry / Q000201:enzymology; D006224:Cricetinae; D004789:Enzyme Activation; D057075:Enzyme Assays / Q000379:methods*; D004795:Enzyme Stability; D004797:Enzyme-Linked Immunosorbent Assay; D054439:Ghrelin / Q000737:chemistry* / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D051381:Rats; D012694:Serine / Q000737:chemistry; D013270:Stomach / Q000166:cytology / Q000201:enzymology; D013379:Substrate Specificity
chemical_list: D002210:Caprylates; D054439:Ghrelin; D012333:RNA, Messenger; D012694:Serine; D000217:Acyltransferases; C534462:ghrelin O-acyltransferase, rat; C031492:octanoic acid