Classification of ghrelin receptor
| Receptor | Ghrelin, GRLN |
| Receptor code | 2.1:GHS:1:GHS1:HUMAN:00 |
| Previous names | GHS-R, GHS-R1a (approved human gene symbol) |
| Structural information | 7TM |
| Human: 366aa (SwissProt Q92847), chr. 3q26.31 (LocusLink 2693) | |
| Rat: 364aa (SwissProt O08725), chr. 2Q24 (LocusLink 84022) | |
| Mouse: 364aa (SwissProt Q99P50), chr. 3A3 (LocusLink 208188) | |
| Functional assays | In vitro pharmacology using human isolated vessels (Wiley and Davenport, 2002) |
| In vitro pharmacology using isolated guinea pig papillary muscle (Bedendi et al., 2003) | |
| Endogenous agonists | Ghrelin (IC50 = 8.1 nM/EC50 = 1.5 nM) = des-Gln14-ghrelin (IC50 = 7.4 nM/EC50 = 1.5 nM) (Matsumoto et al., 2001; Bedendi et al., 2003) |
| Selective agonists | GHRP-2 (IC50 = 0.4 nM) > MK-0677 (IC50 = 0.8 nM) > GHRP-6 (IC50 = 1.5 nM) (cloned rat receptor; McKee et al., 1997) |
| Antagonists | [d-Lys3]-GHRP-6, EP-80317 |
| Antagonist potencies | |
| Radioligand assays | Human hypothalamus, human cardiovascular tissue |
| Radioligands | [125I-His9]-ghrelin, (Kd = 0.22–0.57 nM) (Katugampola et al., 2001) |
| [125I-Tyr4]-ghrelin (Kd = 0.44 nM) (Muccioli et al., 2001) | |
| [125I-Tyr4]-ghrelin (Kd = 0.51 nM) (Bedendi et al., 2003) | |
| Transduction | |
| Mechanism | Coupled to G-α-11 proteins |
| Receptor distribution | Humans, specific [125I-His9]-ghrelin binding was localized to the human vasculature including aorta, coronary arteries, pulmonary arteries, arcuate arteries (in the kidney), and saphenous veins; rats: binding sites were also localized to the vasculature in peripheral tissues as well as the granular layer of the cerebellum in the CNS (Katugampola et al., 2001) |
| Tissue function | Stimulates release of growth hormone from the anterior pituitary, gastric acid secretion, and motility; may alter appetite and energy balance; vasodilation |
aa, amino acid; chr., chromosome.