A map of the SLA complex, or swine major histocompatibility complex (M
HC), class I region was constructed by alignment of yeast artificial c
hromosomes (YACs) harboring MHC class I genes as well as anchor genes
already mapped within the human MHC complex (HLA). Five YACs containin
g 9 anchor genes built a contig of about 1.0-1.2 Nib between the SLA c
lass III BAT1 locus and the olfactory receptor-like genes OLF42., Ten
different SLA class I sequences, including putative allelic forms of p
ublished classical and non-classical SLA class I genes, were assigned
to the 400-kb enclosing centromeric part of the contig. Three addition
al YACs comprising the OLF89 genes and two YACs containing the butyrop
hilin gene were located telomeric to the contig. Comparison between th
e human and porcine MHC complexes showed a perfect conserved order of
anchor genes, whereas no orthologous relationships were found for the
class I loci.