MHC CLASS-I GENE ORGANIZATION IN GREATER-THAN-1.5-MB YAC CONTIGS FROMTHE H2-M REGION

Sixteen yeast artificial chromosome (YAC) clones have been mapped to t he H2-M region at the distal end of the mouse major histocompatibility complex (MHC) on chromosome 17. Analysis of the YACs with single- and multicopy probes yielded a proximal contig spanning a minimum of 800 kb and a distal contig of 700 kb. A probe for the conserved fourth exo n of MHC class I genes detected 19 restriction fragments, including 6 of the 8 previously characterized H2-M class I genes, in the proximal contig. This contig spans the gap from the M to the T region and inclu des the T1 gene. By contrast, only two class I genes, M2 and M3, were found in the distal contig. These two genes, which are both expressed, may mark the end of the MHC. The order among nine class I genes and s even other markers was determined in the cloned DNA from the centromer e as T1, Tu32A, (M1-M7-M8), Tu32B, B30, M6, M4, M5, Mog, Tu42A//M2, Le h525, M3, Tu42B, where the orientation with respect to the centromere is unknown for M1-M7-M8. (C) 1995 Academic Press, Inc.