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The complete swine olfactory subgenome: expansion of the olfactory gene repertoire in the pig genome

Dinh Truong Nguyen1, Kyooyeol Lee1, Hojun Choi1, Min-kyeung Choi1, Minh Thong Le1, Ning Song1, Jin-Hoi Kim1, Han Geuk Seo1, Jae-Wook Oh2, Kyungtae Lee3, Tae-Hun Kim3 and Chankyu Park1*

Author affiliations

1 Department of Animal Biotechnology, Konkuk University, 263 Achasan-ro, Gwangjin-gu, Seoul, 143-701, South Korea

2 Division of Animal Life Science, Konkuk University, Seoul, South Korea

3 Animal Genomics and Bioinformatics Division, National Institute of Rural Development Administration, Suwon, South Korea

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Citation and License

BMC Genomics 2012, 13:584  doi:10.1186/1471-2164-13-584

Published: 15 November 2012



Insects and animals can recognize surrounding environments by detecting thousands of chemical odorants. Olfaction is a complicated process that begins in the olfactory epithelium with the specific binding of volatile odorant molecules to dedicated olfactory receptors (ORs). OR proteins are encoded by the largest gene superfamily in the mammalian genome.


We report here the whole genome analysis of the olfactory receptor genes of S. scrofa using conserved OR gene specific motifs and known OR protein sequences from diverse species. We identified 1,301 OR related sequences from the S. scrofa genome assembly, Sscrofa10.2, including 1,113 functional OR genes and 188 pseudogenes. OR genes were located in 46 different regions on 16 pig chromosomes. We classified the ORs into 17 families, three Class I and 14 Class II families, and further grouped them into 349 subfamilies. We also identified inter- and intra-chromosomal duplications of OR genes residing on 11 chromosomes. A significant number of pig OR genes (nā€‰=ā€‰212) showed less than 60% amino acid sequence similarity to known OR genes of other species.


As the genome assembly Sscrofa10.2 covers 99.9% of the pig genome, our analysis represents an almost complete OR gene repertoire from an individual pig genome. We show that S. scrofa has one of the largest OR repertoires, suggesting an expansion of OR genes in the swine genome. A significant number of unique OR genes in the pig genome may suggest the presence of swine specific olfactory stimulation.

Olfactory receptor; Pigs; Olfaction; OR genes