title: Genetic variability of MHC class II DQB exon 2 alleles in yak (Bos grunniens).
abstract: The major histocompatibility class (MHC) DQ molecules are dimeric glycoproteins revealing antigen presentation to CD(4+) T cells. In the present study, the exon 2 of the MHC class II DQB gene from 32 yaks (Bos grunniens) was cloned, sequenced and compared with previously reported patterns for other bovidae. It was revealed by sequence analyses that there are 25 DQB exon 2 alleles among 32 yaks, all alleles are found to belong to DQB1 loci. These alleles exhibited a high degree of nucleotide and amino acid polymorphisms with most amino acid variations occurring at positions forming the peptide-binding sites. The DQB loci were analyzed for patterns of synonymous (d S) and non-synonymous (d N) substitution. The yak was observed to be under strong positive selection in the DQB exon 2 peptide-binding sites (d N = 0.15, P < 0.001). It appears that this variability among yaks confers the ability to mount immune responses to a wide variety of peptides or pathogens.
authors.affiliation: Faculty of Animal Science and Technology, Yunnan Agricultural University, Kunming, 650201, People's Republic of China.
authors.forename: Yiduo
authors.initials: Y
authors.lastname: He
authors.forename: Dongmei
authors.initials: D
authors.lastname: Xi
authors.forename: Jing
authors.initials: J
authors.lastname: Leng
authors.forename: Tao
authors.initials: T
authors.lastname: Qian
authors.forename: Dan
authors.initials: D
authors.lastname: Jin
authors.forename: Ting
authors.initials: T
authors.lastname: Chen
authors.forename: Chunling
authors.initials: C
authors.lastname: Yang
authors.forename: Tiantian
authors.initials: T
authors.lastname: Hao
authors.forename: Zaiqing
authors.initials: Z
authors.lastname: Yang
authors.forename: Weidong
authors.initials: W
authors.lastname: Deng
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002417:Cattle; D005091:Exons; D014644:Genetic Variation; D000949:Histocompatibility Antigens Class II / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment
chemical_list: D000949:Histocompatibility Antigens Class II