Internal sequence identity plot of the major ULBP cluster. Sequence numbers displayed on the X- and Y-axes indicate alignment orientation, originating in the lower left corner. The center line represents identity; other lines indicate regions of internal sequence identity. Genes are annotated above the figure with arrows indicating orientation. Nucleotide sequences used to construct the major ULBP cluster are listed in Table 1. The duplication of ULBP28-ULBP31 to form ULBP16-ULBP20 is within the red shaded area. The cattle specific repeat regions within ULBP17 and ULBP2 are indicated by red asterisks. The duplication of ULBP7-ULBP9 corresponding to ULBP22-ULBP24 is within the blue shaded area. The duplication of ULBP21-ULBP22 corresponding to ULBP25-ULBP26 is within the green shaded area. The tandem duplications of ULBP9 and ULBP10, ULBP11 and ULBP12, ULBP13 and ULBP14, and ULBP15 are within the yellow shaded area, and lines showing their similarity to the ULBP27 region are within the violet shaded area.