Table 2. List of class A GPCRs included in the study (continued from Table 1).
| Subgrp idx | # GPCRs in subgrp | GPCRs included in the subgroupsa | Natural ligand | Chemical class of natural ligand | Notesc |
| 11 | 6 | S1PR2 (EDG5), S1PR1 (EDG1), S1PR3 (EDG3), S1PR5 (EDG8), LPAR1 (EDG2), LPAR3 (EDG7) | sphingosine 1-phosphate, lysophosphatidic acid (LPAR1, LPAR3) | lipid | |
| 12 | 3 | GPR3, GPR6, GPR12 | sphingosine 1-phosphate | lipid | |
| 13 | 3 | FFAR1 (GPR40), FFAR2 (GPR43), FFAR3 (GPR41) | free fatty acids | lipid | |
| 14 | 7 | PTGDR (PD2R), PTGER1 (PE2R1), PTGER3 (PE2R3), PTGER4 (PE2R4), PTGFR (PF2R), PTGIR (PI2R), TBXA2R (TA2R) | prostaglandins, thromboxane (TA2R) | lipid | |
| 15 | 3 | CYSLTR1 (CLTR1), CYSLTR2(CLTR2), GPR17 | cysteinyl leukotrienes | lipid | |
| 13bd | 4 | FFAR1 (GPR40), FFAR2 (GPR43), FFAR3 (GPR41), GPR42 (pseudogene) | free fatty acids | lipid | |
| 16 | 5 | LPAR4 (P2RY9), LPAR6 (P2RY5), GPR174 (GP174), P2RY10 (P2Y10), PTAFR | lysophosphatidic acid, sphingosine 1-phosphate (P2Y10), platelet activating factor | lipid | o |
| 17 | 5 | RRH (OPSX), OPN3, OPN4, OPN5, RGR | Retinoids | lipid | |
| 18 | 4 | OPN1MW (OPSG), OPN1LW (OPSR), RHO (OPSD), OPN1SW (OPSB) | Retinoids | lipid | |
| 19 | 3 | GPR81, GPR109B (G109B), GPR109A (G109A) | hydroxylated short and medium-chain fatty acids | lipid |
a
The receptors are indicated through their gene name. Uniprot name, when different from the gene name, and common synonyms are listed in parentheses. Orphan receptors are indicated in bold and indicated as ‘o’ in Notes.
c
The symbol “o” indicates that the subgroup has one or more orphan GPCR.
d
Derived from subgroup 13 through the addition of the pseudogene GPR42.