Receptors

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)).

receptors
Sr. No Receptor Organism Length Chromosome Family Sub Family UniProt GenBank #Odorants Details
251 OR4K4P Human 14 4 K NG_002242 0 View
252 OR4K5 Human 323 14 4 K Q8NGD3 NM_001005483 0 View
253 OR4K6P Human 14 4 K NG_002240 0 View
254 OR4K7P Human 18 4 K NG_002235 0 View
255 OR4K8P Human 18 4 K NG_002222 0 View
256 OR4L1 Human 312 14 4 L Q8NH43 NM_001004717 0 View
257 OR4M1 Human 313 14 4 M Q8NGD0 NM_001005500 0 View
258 OR4M2 Human 313 15 4 M Q8NGB6 NM_001004719 0 View
259 OR4N1P Human 14 4 N NG_002243 0 View
260 OR4N2 Human 307 14 4 N Q8NGD1 NM_001004723 0 View
261 OR4N3P Human 15 4 N NR_028067 0 View
262 OR4N4 Human 316 15 4 N Q8N0Y3 NM_001005241 1 View
263 OR4N5 Human 308 14 4 N Q8IXE1 NM_001004724 0 View
264 OR4P1P Human 11 4 P NG_002236 0 View
265 OR4P4 Human 312 11 4 P Q8NGL7 NM_001004124 0 View
266 OR4Q1P Human 15 4 Q NG_004162 0 View
267 OR4Q2P Human 307 14 4 Q P0C623 AF399446 0 View
268 OR4Q3 Human 313 14 4 Q Q8NH05 KP290654 2 View
269 OR4R1P Human 11 4 R NG_002265 0 View
270 OR4R2P Human 11 4 R NG_004231 0 View
271 OR4R3P Human 11 4 R NG_004230 0 View
272 OR4S1 Human 309 11 4 S Q8NGB4 NM_001004725 0 View
273 OR4S2 Human 311 11 4 S Q8NH73 NM_001004059 0 View
274 OR4T1P Human 14 4 T NG_004351 0 View
275 OR4U1P Human 14 4 U NG_004350 0 View
Showing 251 to 275 of total 2067 entries