title: Signatures of positive selection in LY96 gene in vertebrates.
abstract: As a secreted glycoprotein that binds to the extracellular domain of Toll-like receptor 4 (TLR4), Lymphocyte Antigen 96 (LY96), also called myeloid differentiation 2 (MD2), is required for the activation of TLR4 by lipopolysaccharide (LPS) and plays an important role in innate immunity, which is the first line of defence against microbial infections. Previous studies have proposed that mammalian toll-like receptors (TLRs) have evolved under diversifying selection due to their role in pathogen detection. Given the fact that LY96 is highly functionally linked to TLR4, it would be interesting to test whether LY96 is under the intense pressure of natural selection. To investigate the natural selection hypothesis, we compared the coding sequences from 13 vertebrates and evaluated the molecular evolution of LY96 gene in these species. Result shows that natural selection at exon 4 has indeed played a role in shaping the function of LY96 in the course of evolution. In addition to the study of Nakajima, we found the two branch nodes with Ka/Ks ratios greater than 1: the one leading to cow and pig and the other to rabbit and the primates.
authors.affiliation: Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai 200433, People's Republic of China.
authors.forename: Tonghai
authors.initials: T
authors.lastname: Dou
authors.forename: Maobin
authors.initials: M
authors.lastname: Fu
authors.forename: Yixia
authors.initials: Y
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.forename: Zhengshi
authors.initials: Z
authors.lastname: Wang
authors.forename: Zhengqian
authors.initials: Z
authors.lastname: Bian
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhou
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019143:Evolution, Molecular; D005091:Exons; D006801:Humans; D051218:Lymphocyte Antigen 96 / Q000737:chemistry / Q000235:genetics*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D017433:Protein Structure, Secondary; D012641:Selection, Genetic
chemical_list: C495377:LY96 protein, human; D051218:Lymphocyte Antigen 96