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
2026 MOR146-8P Mus musculus 309 7 E Q7TRF7 NM_001012265 0 View
2027 MOR246-2 Mus musculus 324 4 K Q8VEX3 NM_146319 0 View
2028 MOR282-1 Mus musculus 314 2 Z E9Q4J3 NM_146539 0 View
2029 MOR190-3P Mus musculus 8 K NG_002128 0 View
2030 MOR253-13P Mus musculus 310 13 A Q7TRT5 NM_001011867 0 View
2031 MOR203-8P Mus musculus NG_001767 0 View
2032 MOR267-17 Mus musculus 315 10 H K7N6Q1 NM_010998 0 View
2033 MOR256-31 Mus musculus 317 2 W Q7TQT8 NM_010984 0 View
2034 MOR23-2 Mus musculus 315 52 AB L7N224 NM_001011845 0 View
2035 MOR263-8P Mus musculus 1 F NG_001905 0 View
2036 MOR110-8 Mus musculus 314 6 C Q7TRI2 NM_001011797 0 View
2037 MOR114-10P Mus musculus 6 C NG_001871 0 View
2038 MOR187-4 Mus musculus 320 8 K Q8VGS2 NM_001177857 0 View
2039 MOR182-9 Mus musculus 305 Q7TS36 NM_001011792 0 View
2040 MOR189-5P Mus musculus NG_001845 0 View
2041 MOR106-10 Mus musculus 311 11 G L7N1Y5 NM_207133 0 View
2042 MOR203-7P Mus musculus 309 5 AK Q7TRA2 NM_001011785 0 View
2043 MOR137-2 Mus musculus 312 1 J Q7TRY6 NG_021447 0 View
2044 MOR182-11P Mus musculus 305 5 AC Q7TS37 NM_001011736 0 View
2045 MOR135-5 Mus musculus 312 1 E Q7TRX8 NM_207224 0 View
2046 MOR245-1 Mus musculus 314 4 F Q8VG12 NM_146742 0 View
2047 MOR15-1 Mus musculus 323 51 AA K7N609 NM_146727 1 View
2048 MOR106-6 Mus musculus 311 11 G Q8VF70 NM_146430 0 View
2049 MOR150-1P Mus musculus 315 7 G Q8VFF2 NM_207145 0 View
2050 MOR14-7P Mus musculus 316 51 F Q7TRS5 NM_001011536 0 View
Showing 2026 to 2050 of total 2067 entries