The genomic organisation and nucleotide sequence of the HLA-SB(DP) alpha gene

We have isolated a unique fragment of the HLA-DR alpha gene and probed human genomic DNA at low stringency to search for homologous sequences. A minimum of six non-polymorphic cross-hybridizing high molecular weight fragments were found in all DNAs examined. In order to obtain molecular clones of these cross-hybridizing fragments, we constructed lambda and cosmid libraries of human DNA and screened them at low stringency with the HLA-DR alpha gene specific subclone. We have isolated clones corresponding to each of the six fragments and, in this paper, describe those which contain the gene encoding HLA-SB(DP) alpha.