Odorant receptors may be categorized into two groups, ref 3 Class I (fish-like) and Class II (tetrapod-specific) odorant receptors. Class I odorant receptors are specific for recognizing water soluble odorants, whereas Class II odorant kinase inhibitor Imatinib receptors bind airborne odorants [27]. Expression of Class I odorant receptors has already been reported in Inhibitors,Modulators,Libraries rats [28] and in human [29]. Class II families which can further be classified into 19 phylogenetic clades are all present in more than one chromosome each, Inhibitors,Modulators,Libraries except for the very small family 12 [27]. In humans, the size of the receptor family Inhibitors,Modulators,Libraries genes is estimated at the range from 500 to 1,000 [30]. Such large number of odorant Inhibitors,Modulators,Libraries receptor genes implies that the first steps of odorant recognition may be accomplished within the primary sensory neurons themselves.
Thus odorant receptor seems Inhibitors,Modulators,Libraries to be excellent for sensors differentiating numerous chemicals, although only one third of these genes are functional [31].2.4. Expression Inhibitors,Modulators,Libraries of odorant receptors in the olfactory epitheliumExpression of odorant receptors in the olfactory epithelium demonstrates an unusual spatial distribution [32, 33]. In situ hybridization studies show that mRNAs for odorant receptors are expressed within one of several broad, non-overlapping zones. Within a zone which occupies about a quarter of the olfactory epithelium, odorant receptors are expressed in a random manner [32].
Recent observations, however, of overlapping zones in the olfactory epithelium [34-36] imply that our understanding of expression of odorant receptors in the olfactory epithelium is far beyond complete.
Most studies have been Inhibitors,Modulators,Libraries done on the expression and distribution of odorant receptors at the message level, however little information Inhibitors,Modulators,Libraries is available at the protein level. Using polyclonal antibodies raised against some odorant receptors, expression of an odorant receptor in rats is visualized as early as E14 in a zonally restricted pattern [37]. The expression of odorant receptors is restricted mostly to the cilia and dendritic knobs of OSNs. The cilia-specific expression of odorant receptors supports a primary role for odorant receptors in the olfactory transduction [38-40].2.5.
Heterologous expression of odorant receptorsThere has been little knowledge about the ligand specificity of individual odorant receptors in any species, due to difficulties in expressing GSK-3 odorant receptors in heterologous systems.
selleck chem inhibitor Dacomitinib The primary role of odorant receptors is certainly to detect environmental odorous chemicals. However, difficulties of heterologous expression of odorant receptors severely limited studies for functional confirmation of such role. The most convincing observation concerning function were initially reported by genetic DAPT secretase studies in C. elegans, which demonstrated that a mutant lacking odorant receptors lost its ability to detect a specific odor [41].