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
1901 MOR256-19 Mus musculus 317 17 2 G Q8VFC1 NM_146487 0 View
1902 MOR256-49 Mus musculus 313 17 2 H Q7TRI8 NM_001005481 0 View
1903 MOR256-5 Mus musculus 312 17 2 N Q8VG95 NM_146832 0 View
1904 MOR218-4 Mus musculus 320 17 14 J Q8C0S2 NM_001013575 0 View
1905 MOR256-29 Mus musculus 312 17 2 H Q6UAH2 NM_146456 0 View
1906 MOR121-2P Mus musculus 17 11 A NG_001937 0 View
1907 MOR256-33 Mus musculus 317 17 2 G Q8VFC1 NM_207155 0 View
1908 MOR256-32P Mus musculus 386 17 2 I Q6UAH0 NM_001011518 0 View
1909 MOR256-6 Mus musculus 312 17 2 N Q8VG94 NM_146831 0 View
1910 MOR256-48 Mus musculus 312 17 2 N Q8VEY4 NM_146332 0 View
1911 MOR256-7 Mus musculus 312 17 2 N Q8VG72 NM_146807 0 View
1912 MOR250-4 Mus musculus 308 17 12 D Q920Y9 NM_001011721 0 View
1913 MOR263-7 Mus musculus 321 17 10 A Q5CZY0 AY317915 0 View
1914 MOR256-38 Mus musculus 164 17 2 H A0A140LHN3 NG_001939 0 View
1915 MOR256-39P Mus musculus 312 17 2 H Q6UAH1 NM_001011813 0 View
1916 MOR121-4P Mus musculus 17 11 A NG_001935 0 View
1917 MOR218-11P Mus musculus 310 17 14 J Q7TRJ8 NM_001011753 0 View
1918 MOR263-11 Mus musculus 17 NG_001795 0 View
1919 MOR256-40P Mus musculus 312 17 2 N Q8VG72 NM_130868 0 View
1920 MOR250-5 Mus musculus 322 17 A0A2I3BRX0 NG_028225 0 View
1921 MOR250-6 Mus musculus 322 17 A0A2I3BQG5 NG_028227 0 View
1922 MOR121-3P Mus musculus 17 11 A NG_001936 0 View
1923 MOR250-7 Mus musculus 312 17 12 D Q6UAF7 NG_028226 0 View
1924 MOR239-3 Mus musculus 310 19 4 D Q8VFV0 NM_146680 0 View
1925 MOR239-1 Mus musculus 311 19 4 D Q8VG74 NM_146809 0 View
Showing 1901 to 1925 of total 2067 entries