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
1976 MOR266-5 Mus musculus 318 19 10 V Q7TQS3 NM_001011524 0 View
1977 MOR202-21 Mus musculus 19 5 B NG_002079 0 View
1978 MOR239-7 Mus musculus 313 19 4 D Q8VFV1 NM_001011853 0 View
1979 MOR211-4P Mus musculus 316 19 9 I Q7TQQ2 NM_001011850 0 View
1980 MOR202-23 Mus musculus 19 5 B NG_002013 0 View
1981 MOR214-6 Mus musculus 312 19 5 AN Q7TQR7 NM_001011839 0 View
1982 MOR215-4 Mus musculus 319 19 A0A140LHS9 NG_002003 0 View
1983 MOR266-6P Mus musculus 316 19 10 W Q7TQQ5 NM_001011832 0 View
1984 MOR212-4P Mus musculus 311 19 9 Q Q7TQQ3 NM_001011831 0 View
1985 MOR214-7P Mus musculus 19 5 Q NG_001902 0 View
1986 MOR266-10 Mus musculus 343 19 10 Q Q7TQS2 NM_001011775 0 View
1987 MOR202-38 Mus musculus 314 19 5 B F6QVZ8 NM_207132 0 View
1988 MOR211-3P Mus musculus 19 9 I NG_002104 0 View
1989 MOR202-25P Mus musculus 19 5 BC NG_002011 0 View
1990 MOR202-27P Mus musculus 19 5 B NG_002009 0 View
1991 MOR202-28 Mus musculus 307 19 5 B Q7TQR2 NM_001011841 0 View
1992 MOR202-30P Mus musculus 19 5 B NG_002006 0 View
1993 MOR202-31P Mus musculus 19 5 U NG_002005 0 View
1994 MOR239-8P Mus musculus 19 4 D NG_001893 0 View
1995 MOR133-4P Mus musculus 19 NG_001892 0 View
1996 MOR128-2 Mus musculus 332 1 AA Q8VEU7 NM_146292 2 View
1997 MOR216-1 Mus musculus 309 5 BH Q8VF35 NM_146390 0 View
1998 MOR102-1 Mus musculus 315 13 AE Q8VF43 NM_146398 0 View
1999 MOR264-16P Mus musculus 310 11 N Q7TQW3 NM_001011794 0 View
2000 MOR106-13P Mus musculus 323 11 G Q7TRM0 NM_001011738 3 View
Showing 1976 to 2000 of total 2067 entries