HGNC Approved Gene Symbol: OBP2B
Cytogenetic location: 9q34.2 Genomic coordinates (GRCh38) : 9:133,205,279-133,223,255 (from NCBI)
The first step in the process of olfaction is the solubilization of hydrophobic molecules in the hydrophilic nasal mucus. Odorant-binding proteins, believed to transport these molecules within the mucus, are members of the lipocalin family. The presence of 2 genes homologous to LCN1 (151675) in the rat raised the question of whether additional LCN1-related genes were present in the human genome. Lacazette et al. (2000) identified human lipocalins involved in odorant-binding representing a gene family located on 9q34. Two mRNAs, OBP2A (164320) and OBP2B, were 97.5% identical to each other and 63% identical to LCN1. OBP2A and OBP2B were differentially expressed in secretory structures. The OBP2A gene was strongly expressed in the nasal structures, salivary and lachrymal glands, and lung, thereby having an oral-sphere profile. On the other hand, the OBP2B gene was more strongly expressed in genital-sphere organs such as prostate and mammary glands. Both were expressed in the placenta and male vas deferens. Alternatively spliced mRNAs resulting in proteins with different C termini were generated from each of the 2 genes. Based on the proposed history of successive genomic duplication, Lacazette et al. (2000) demonstrated the recruitment of exons within intronic DNA generating diversity. This was consistent with a positive selection pressure in vertebrate evolution in the intron-late hypothesis.
Lacazette et al. (2000) determined that the OBP2B gene contains 7 exons, in a structure consistent with genes of the lipocalin family.
Chromosome in situ hybridization and somatic hybrid analysis indicated that if human homologs of rat odorant-binding proteins existed, they would be found in the 9q34 region. Lacazette et al. (2000) identified human lipocalins involved in odorant-binding, including OBP2B, in a region on chromosome 9q34 representing a gene family produced by genomic duplications.
Lacazette, E., Gachon, A. M., Pitiot, G. A novel human odorant-binding protein gene family resulting from genomic duplicons at 9q34: differential expression in the oral and genital spheres. Hum. Molec. Genet. 9: 289-301, 2000. [PubMed: 10607840] [Full Text: https://doi.org/10.1093/hmg/9.2.289]