Olfactory Receptors (ORs) are the physical barriers between the environment and the brain. ORs are members of the GPCR-rhodopsin family, which is involved in cell recognition, signal transduction activation, and sense mediation. OR is made up of seven transmembrane (TM) helical domains bound by three putative extracellular loops (EL) and three putative intracellular loops (IL), an extracellular N-terminus, and an intracellular C-terminus. At the intersection of TM3 and IL2, the intracellular loop includes a conserved sequence motif, the aspartate-arginine-tyrosine (DRY) amino acid motif, which is a hallmark of GPCRs. The TM1, TM2, and TM7 are all conserved. The binding site specificity is determined by the amino acid side chains of the central TM domains, which are structurally diverse. The binding pocket of ORs has a hydrophobic environment, indicative of hydrophobic interactions between odorants and ORs. The binding specificity of ORs is influenced not only by the central TM-domains hyper-variable region, but also by the N-termini and C-termini. Both terminals are small, with only about 20 amino acids each. The conserved cysteine residues in the EL1 and EL2-loops are involved in inter- and intramolecular disulphide linkages. One of the three cysteine restudies in EL2-loop has a specific role. A metal binding site is formed by the sequence motif (HXXC[DE]) in EL2-loop. On binding with Zn(II) or Cu, the EL2-loop transforms into a -helical structure confirmation (eighth helix) (II).When an odorant with a high affinity for metal ions replaces one of the metal-ligated amino acids in the EL2-loop, ORs undergo structural rearrangement, which is necessary for the activation of G-olf proteins attached to OR receptors. On the cytoplasmic side of the TM domains, the sequence motifs KAFSTC, PMYFFL, and YRDYAM play a role in OR folding and activation. The amino acid residues on the extracellular side of TM domains are variable, indicating a wide range of possible odorant recognition sites.

OlfactionBase lists 2067 ORs from two species (Human (851) and Mus musculus (1216)).

Sr. No Receptor Organism Length Chromosome Family Sub Family UniProt GenBank #Odorants Details
1851 MOR182-1 Mus musculus 307 16 5 AC Q8VGQ3 NM_146995 1 View
1852 MOR182-2 Mus musculus 308 16 5 AC Q7TS38 NM_146994 0 View
1853 MOR184-8 Mus musculus 318 16 Q8VGQ1 NM_146993 0 View
1854 MOR182-3 Mus musculus 306 16 5 AC Q8VGP9 NM_146992 0 View
1855 MOR182-4 Mus musculus 306 16 5 AC Q8VGP9 NM_146991 0 View
1856 MOR273-1 Mus musculus 313 16 2 AJ Q7TS51 NM_146958 6 View
1857 MOR273-2 Mus musculus 313 16 2 AJ Q8VGL6 NM_146957 0 View
1858 MOR183-1 Mus musculus 309 16 5 H E9PYP4 NM_146779 0 View
1859 MOR182-5 Mus musculus 305 16 5 AC Q7TS37 NM_146486 0 View
1860 MOR183-3 Mus musculus 309 16 Q8VFB8 AY317282 0 View
1861 MOR279-1 Mus musculus 313 16 2 M Q8VFA2 NM_146466 0 View
1862 MOR279-2 Mus musculus 315 16 2 M Q8VF87 NM_146451 0 View
1863 MOR183-9 Mus musculus 309 16 5 H Q8VEX5 NM_146321 0 View
1864 MOR184-9 Mus musculus 317 16 5 K Q7TS48 NM_001011662 0 View
1865 MOR182-8 Mus musculus 306 16 5 AC Q7TS40 NM_001011808 0 View
1866 MOR131-2P Mus musculus 16 1 F NG_001944 0 View
1867 MOR182-7P Mus musculus 306 16 5 AC Q7TS42 NM_001005524 0 View
1868 MOR183-5P Mus musculus 309 16 5 H Q7TS45 NM_001011807 0 View
1869 MOR113-6P Mus musculus 16 5 H NG_001920 0 View
1870 MOR0-9P Mus musculus 16 NG_001898 0 View
1871 MOR273-3P Mus musculus 313 16 2 AJ Q7TS53 NM_001011855 0 View
1872 MOR271-1 Mus musculus 312 16 21 L Q8VF05 NM_146357 20 View
1873 MOR272-1 Mus musculus 312 16 2 L Q8VGJ5 NM_146935 18 View
1874 MOR249-2 Mus musculus 317 17 5 V Q7TRK2 NM_146328 0 View
1875 MOR218-2 Mus musculus 321 17 14 J Q923Q6 NM_146632 0 View
Showing 1851 to 1875 of total 2067 entries