Table 1.
Five multigene families of GPCRs for mammalian chemosensory systems
| OR | V1R | V2R | T1R | T2R | |
|---|---|---|---|---|---|
| Expression | Olfactory epithelium | VNO | Taste buds | ||
| Ligands | Odorants | Volatile pheromone | Peptide pheromone | Sweet/umami tastants | Bitter tastants |
| Exons | Single | Single | Multiple | Multiple | Single |
| Species | # of genes | ||||
| Human | 398 (442) | 5 (115) | 0 (20) | 3 | 24 (10) |
| Chimpanzee | 397 (442) | 4 (102) | 0 (17) | 3 | 25 (12) |
| Macaque | 350 (340) | 0 (60) | 0 (11) | 3 | 27 (14) |
| Marmoset | 352 (236) | 8 (55) | 0 (8) | 3 | 20 (10) |
| Mouse | 1,130 (236) | 239 (153) | 121 (158) | 3 | 36 (7) |
| Rat | 1,207 (560) | 108 (108) | 79 (142) | 3 | 36 (5) |
| Dog | 811 (289) | 9 (54) | 0 (9) | 3 | 14 (4) |
| Cow | 1,186 (1,098) | 40 (43) | 0 (16) | 3 | 17 (12) |
The table includes the numbers of intact genes, along with the total of truncated genes and pseudogenes in parentheses. The numbers of OR genes are derived from Niimura et al. (2014, 2018), V2R and T1R genes are from Nei et al. (2008), V1R genes are from Nei et al. (2008) and Young et al. (2010), and T2R genes are from Hayakawa et al. (2014).