| Family | Class A | Class B (Secretin) | Class C (Glutamate) | Adhesion | Frizzled |
| Receptors with known ligands | 197a | 15 | 12 | 0 | 11 |
| Orphans | 87 (54)a | ‐ | 8 (1)a | 26 (6)a | 0 |
| Sensory (olfaction) | 390b,c | ‐ | ‐ | ‐ | ‐ |
| Sensory (vision) | 10d opsins | ‐ | ‐ | ‐ | ‐ |
| Sensory (taste) | 30c taste 2 | ‐ | 3c taste 1 | ‐ | ‐ |
| Sensory (pheromone) | 5c vomeronasal 1 | ‐ | ‐ | ‐ | ‐ |
| Total | 719 | 15 | 22 | 33 | 11 |
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