Ghrelin and des-acyl ghrelin: two major forms of rat ghrelin peptide in gastrointestinal tissue.
Ghrelin, a novel peptide purified from stomach, is the endogenous ligand for the growth hormone secretagogue receptor and has potent growth hormone-releasing activity. The Ser3 residue of ghrelin is modified by n-octanoic acid, a modification necessary for hormonal activity. We established two ghrelin-specific radioimmunoassays; one recognizes the octanoyl-modified portion and another the C-terminal portion of ghrelin. Using these radioimmunoassay systems, we found that two major molecular forms exist-ghrelin and des-n-octanoyl ghrelin. While ghrelin activates growth-hormone secretagogue (GHS) receptor-expressing cells, the nonmodified des-n-octanyl form of ghrelin, designated as des-acyl ghrelin, does not. In addition to these findings, our radioimmunoassay systems also revealed high concentrations of ghrelin in the stomach and small intestine.
Hosoda
H
H
Department of Biochemistry, National Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka, 565-8565, Japan.
Kojima
M
M
Matsuo
H
H
Kangawa
K
K
D000595:Amino Acid Sequence; D000818:Animals; D004386:Duodenum / Q000378:metabolism*; D005753:Gastric Mucosa / Q000378:metabolism*; D054439:Ghrelin; D007136:Immunoglobulins / Q000276:immunology; D008297:Male; D008969:Molecular Sequence Data; D036361:Peptide Hormones; D010455:Peptides / Q000032:analysis* / Q000276:immunology; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution
D054439:Ghrelin; D007136:Immunoglobulins; D036361:Peptide Hormones; D010455:Peptides; C422650:ghrelin, des-n-octanoyl