Table 2.
Classification of THR-like receptors: The THR-like family is classified into 11 subfamilies, with functional details of the members and their corresponding ligands.
| S. No. | Subfamily group | Subfamily Name | Subfamily Members | Ligands | Functional role of the receptor |
|---|---|---|---|---|---|
| 1. | A | Thyroid hormone receptor | TRα (Thyroid hormone receptor alpha) TRβ (Thyroid hormone receptor beta) |
Thyroid hormone | Regulation of metabolism, heart rate, and development of organisms |
| 2. | B | Retinoic acid receptor | RARα (Retinoic acid receptor-α) RARβ (Retinoic acid receptor-β) RARγ (Retinoic acid receptor-γ) |
Vitamin A and related compounds | Cell differentiation, cell proliferation, and apoptosis |
| 3 | C | Peroxisome proliferator-activated receptor | PPARα (Peroxisome proliferator-activated receptor-α) PPAR-β/δ (Peroxisome proliferator-activated receptor-β/δ) PPARγ (Peroxisome proliferator-activated receptor-γ) |
Fatty acids, prostaglandins | Cellular differentiation, development, and metabolism (carbohydrate, lipid, protein) and tumorigenesis |
| 4. | D | Rev-ErbA | Rev-ErbAα Rev-ErbAβ |
Heme | Regulators of clock gene |
| 5. | E | E78C-like (only found in arthropod, trematode, mollusk, nematode) |
Eip78C (Ecdysone-induced protein 78C) | – | Development and regulate key processes during oogenesis. control ecdysone signaling in insects driving metamorphosis and molting |
| 6. | F | RAR-related orphan receptor | RORα (RAR-related orphan receptor-α) RORβ (RAR-related orphan receptor-β) RORγ (RAR-related orphan receptor-γ) |
Cholesterol, ATRA | Development of the cerebellum and lymph nodes, lipid metabolism, immune response, maintenance of bone. Circadian rhythm, bone metabolism, and retinal neurogenesis, Lymph node development and immune response, survival of T helper 17 cells |
| 7. | G | CNR14-like (nematode) | Sex-1 (Steroid hormone receptor cnr14) | – | |
| 8. | H | Liver X receptor-like | EcR (Ecdysone receptor, EcR (arthropod)) LXRβ (Liver X receptor-β) LXRα (Liver X receptor-α) FXR (Farnesoid X receptor) FXR-β (Farnesoid X receptor-β) |
Ecdysteroids Oxysterols Bile acid Orphan |
regulators of cholesterol, fatty acid, and glucose homeostasis |
| 9. | I | Vitamin D receptor-like | VDR (vitamin D receptor) PXR (Pregnane X receptor) CAR (Constitutive androstane receptor) |
Vitamin D Xenobiotics Androstane |
Mineral Metabolism Detoxification Drug Metabolism and bilirubin clearance |
| 10. | J | Hr96-like | Hr96/Daf-12 (Nuclear hormone receptor HR96) | Cholestrol/dafachronic acid | |
| 11. | K | Hr1-like | Nuclear hormone receptor HR1 | – |