ISOLATION AND PROMOTER MAPPING OF THE GENE ENCODING MURINE COSTIMULATORY FACTOR B7-1

B7-1 is one of the co-stimulatory factors which plays an important rol e in immunity. We have cloned and functionally mapped the promoter of the murine B7-1 gene using transient transfection assays in mouse L (t k(-)) cells. The B7-1 basal promoter consists of three positively regu lated regions. The distal region, located at -2597 to -1555, contains an assortment of putative transcription factor binding sites. The prox imal upstream region, located at -130 to -110, contains a tandem repea t sequence 5'-GTGTTCTAGTGTT-3'. A downstream region is positioned at 269 to +25. We have also identified an alternatively spliced form of t he murine B7-1 gene in L (tk(-)) cells.