Table 2.
Gene number and receptor subfamilies of the human rhodopsin GPCRs involved in feeding and the sequence homologs identified in C. elegans and D. melanogaster.
| Rhodopsin | Subfamily | Human | C. elegans | D. melanogaster |
|---|---|---|---|---|
| α-Group | Melanocortin | 5 | ni | ni |
| β-Group | Gastrin-cholecystokinin | 2 | 2 | 2 |
| Neurokinin | 3 | 6 | 5 | |
| Neuropeptide FF | 2 | |||
| Orexin | 2 | |||
| Neuropeptide Y | 6 | 12 | 4 | |
| Bombesin | 3 | ni | 2 | |
| Ghrelin/obestatin | 2 | 6 | 5 | |
| Neuromedin U | 2 | |||
| γ-Group | Somatostatin | 5 | 6 | 2 |
| Galanin | 3 | 3 | 2 | |
| Melanin concentrating hormone | 2 | ni | ni | |
| Total | 37 | 35 | 22 |
The total number of receptor genes in human, C. elegans and D. melanogaster is indicated. In C. elegans and D. melanogaster the homologs of the human Neurokinin/Neuropeptide FF/Orexin receptors and Ghrelin-Obestatin/Neuromedin U receptors were grouped due to their high sequence relatedness (Hewes and Taghert, 2001). ni, not identified.