Spatial arrangement of pig MHC class I sequences

Bacterial artificial chromosome (BAC) clones were assigned within the pig m ajor histocompatibility complex (Mhc) by polymerase chain reaction-screenin g and Southern blot hybridization using sequence-tagged site (STS) markers and BAC end-rescued sequences. In all, 35 BAC clones were discovered contai ning 12 anchor genes of the SLA class I region and two genes of the SLA cla ss III region. Twenty of these 35 clones comprised two distinct class I gen e clusters, each spanning about 100 kilobases. One cluster enclosed three c lass I related genes (SLA-6 to -8) and two genes (MIC-1 and MIC-2) more dis tantly related to class I. The other cluster enclosed typical class I genes , of which three (SLA-1, -2, and -3) were transcribed by fibroblasts homozy gous for the H01 haplotype which we used to construct a pig BAC library. Or dered clones are certainly helpful in isolating agronomically, biologically , and medically important genes. They would also be useful for inducing gen etic modifications in pig cell lines.