Cloning and characterization of ovine β2-microglobulin cDNAs

Abstract

Beta-2-microglobulin (β 2m) is the light chain of the major histocompatibility complex (MHC) class I cell surface heterodimer. β 2m is well conserved across most species with few polymorphisms seen within species. The aims of this study were to clone and express ovine β 2m and investigate if allelic variation of ovine β 2m exists. Ovine β 2m clones were isolated from five sheep of three breeds by reverse-transcription polymerase chain reaction (RT-PCR). Sequence analysis showed that four ovine β 2m sequences were obtained. Within breeds and individual animals there was evidence of allelic variation of ovine β 2m. An expression system was established to express one of the alleles with an ovine MHC class I cDNA clone in human embryo kidney cells (HEK293) and quail cells (QT35). Transfection experiments showed that ovine β 2m was expressed and directed the expression of ovine MHC class I heavy chain to the cell surface of the transfected cells. Both bovine and human β 2m supported ovine MHC class I heavy chain cell surface expression.