A NOVEL GENE, G7E, RESEMBLING A VIRAL ENVELOPE GENE, IS LOCATED AT THE RECOMBINATIONAL HOT-SPOT IN THE CLASS-III REGION OF THE MOUSE MHC

DNA sequence analysis of a segment of 15 kb, situated between G7b and G7a and present in the mouse but absent in human, revealed about 11 kb of DNA harboring a large number of repetitive sequences and 4 kb harb oring a novel gene, G7e. This gene is transcribed in lymphoid tissues, having a 3-kb mRNA. The cDNA sequence of G7e shows stretches of nucle otide homology with murine leukemia virus (MuLV) envelope genes, and t he predicted protein encompasses viral envelope motifs. The finding of a gene resembling MuLV envelope genes, flanked by a long terminal rep eat and gag- and pol-like sequences, leads to the assumption that G7b and G7a in the mouse were separated through the insertion of a proviru s, an event that might have taken place even before speciation of rat and mouse. The 15-kb interval forms a part of a 50-kb region, between Hsp70.3 and G7, where recombination preferentially takes place. Severa l disease susceptibility genes have been mapped to this same interval. The position of G7e in or in the vicinity of a recombinational hot sp ot might not be coincidental. The presence of adjacent putative recomb ination regulatory sequences is suggestive for the location of the cro ssover sites of recombination in this interval. (C) 1996 Academic Pres s, Inc.