Molecular cloning and characterization of SRAM, a novel insect Rel/Ankyrin-family protein present in nuclei

Previously, we purified a 59-kDa protein that binds to the KB motif of the Sarcophaga lectin gene. Here we report its cDNA cloning and some of its cha racteristics as a novel member of the Rel/Ankyrin-family. This protein, nam ed SRAM, contained a Rel homology domain, a nuclear localization signal and 4 ankyrin repeats, but lacked the Ser-rich domain and PEST sequence that R elish contained, We found that SRAM was localized in the nuclei of NIH-Sape -4 cells, which are an embryonic cell line of Sarcophaga, The Sarcophaga le ctin gene promoter containing tandem repeats of the kappa B moths was activ ated in NIH-Sape-4 cells. In Drosophila mbn-2 cells, Dif alone activated th is reporter gene and a cooperative effect was detected when SRAM and Dif we re co-transfected, although SRAM alone did not activate it. This is the fir st report of a Rel/Ankyrin molecule that exists in the nuclei.