부산대학교 도서관

Animals with fully characterised major histocompatibility complex ( MHC) regions are often used to explore the molecular interactions that control the induction of adaptive immunity. The ovine MHC includes two DQA loci, termed DQA1 and DQA2. However, in a minority of haplotypes the DQA1 locus appears absent ( DQA1 null) and is replaced by a second locus termed , DQA2-like. This raises a number of questions regarding the origins and function of the DQA2-like sequences. To address this, we have analysed DQA diversity associated with 10 MHC haplotypes, including two classified as DQA1 null. Pair-wise comparison between full-length DQA transcripts from each haplotype identified unique diversity throughout the DQA2-like sequences. Conserved orthologues of the DQA2-like sequences were identified in cattle and goat, and phylogenetic analysis clustered exons 1 and 2 with DQA2 whereas the remainder of the sequence clustered with DQA1. The DQA2-like allelic lineage appears functional and to have arisen from an ancient interlocus recombination between DQA1 and DQA2 loci which predates Bovidae speciation. [ABSTRACT FROM AUTHOR]