Lukacs et al. BMC Genomics 2010, 11:154 http://www.biomedcentral.com/1471-2164/11/154 Page 3 of 17 Figure 1 Gene organization of Atlantic salmon MHC class I regions. LG15 is the Atlantic salmon MHC IA region with the previous sequenced BACs 30C23, 868O01, 92I04, 714P22 and 523M19 extended with 129P21. LG3-1 is the Atlantic salmon MHC IB region with the previous sequenced BACs 8I14, 424M17, 15L20 and 189M18 extended with 439H13 and 68O19, and LG3-2 is the allelic BAC 439J08. LG10 and LG14 containing the BACs 114L13 and LG14 respectively. Genbank accession numbers are indicated after the BAC clone name. Locus designation is based on sequence identity to matching ESTs and human nomenclature is used. The regions are drawn to scale. Color code: red is MHC class I genes, yellow is TAP genes, green is proteasome genes, blue is human extended MHC class II region genes, purple is human class I region genes, grey is non-human class I region genes, pseudogenes are striped.