Isolation and promoter mapping of the gene encoding murine co-stimulatory factor B7-1

B7-1 is one of the co-stimulatory factors which plays an important role in immunity. We have cloned and functionally mapped the promoter of the murine B7-1 gene using transient transfection assays in mouse L (tk −) cells. The B7-1 basal promoter consists of three positively regulated regions. The distal region, located at −2597 to −1555, contains an assortment of putative transcription factor binding sites. The proximal upstream region, located at −130 to −110, contains a tandem repeat sequence 5′- GTGTTCTAGTGTT-3′. A downstream region is positioned at +269 to +25. We have also identified an alternatively spliced form of the murine B7-1 gene in L (tk −) cells.