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
2051 MOR203-5P Mus musculus 309 5 AK Q7TRA1 NM_001011534 0 View
2052 qMOR40-7P Mus musculus 318 56 B Q7TRU7 NM_001011858 0 View
2053 MOR267-11 Mus musculus 309 10 X F8VQB1 NM_207137 0 View
2054 MOR23-3P Mus musculus 52 AB NG_001864 0 View
2055 MOR23-4P Mus musculus 319 52 AB Q7TRR2 NM_001011793 0 View
2056 MOR135-24 Mus musculus 312 1 E A0A0U1RNJ4 NM_001159775 0 View
2057 MOR256-44P Mus musculus 2 Y NG_001857 0 View
2058 MOR211-6P Mus musculus NG_001856 0 View
2059 MOR211-7P Mus musculus NG_001855 0 View
2060 MOR218-6P Mus musculus 323 14 J Q7TRJ0 NM_001011829 0 View
2061 MOR188-7 Mus musculus 313 8 K Q7TR72 NM_207134 0 View
2062 MOR245-19P Mus musculus 312 4 F Q7TQX1 NM_001011787 0 View
2063 MOR0-15P Mus musculus 321 A0A140LHT7 NG_001842 0 View
2064 MOR193-1 Mus musculus 311 8 K A0A1L1SRK6 NM_001011771 0 View
2065 MOR204-33P Mus musculus 306 5 P Q7TRV2 NM_001005488 0 View
2066 MOR245-24P Mus musculus 326 A0A288CFY5 NG_029452 0 View
2067 MOR170-1 Mus musculus 316 9 8 C Q8VGD5 NM_146875 2 View
Showing 2051 to 2067 of total 2067 entries