Purification, characterization, and cDNA cloning of ABP-2 (arylphorin gene-specific binding protein-2) that specifically binds to the ABP-1-binding sequence in the arylphorin gene of Sarcophaga peregrina.

Previously, we demonstrated that ABP-1 (arylphorin gene-specific binding protein-1), which is suggested to be the transcriptional activator of the arylphorin gene of Sarcophaga peregrina, is present in NIH-Sape-4 cells, which do not express arylphorin. As well as ABP-1, these cells were found to contain another protein (ABP-2) that probably binds to the same sequence as that to which ABP-1 binds [Adachi, N., Kubo, T., and Natori, S. (1993) J. Biochem. 114, 55-60]. We purified ABP-2 from a nuclear extract of NIH-Sape-4 cells and compared its DNA-binding activity with that of ABP-1. Both ABP-1 and ABP-2 were found to bind to the same sequence in the arylphorin gene with the same affinity and stability, but an ABP-2-specific hypersensitive site was detected by DNase I footprinting analysis. Analyses of proteolytic fragments suggested that both ABP-1 and ABP-2 have Zn fingers showing high similarity with that of AEF-1, a transcriptional repressor of the Drosophila melanogaster alcohol dehydrogenase gene that binds to a sequence very similar to that binding ABP-1 and ABP-2. We isolated a candidate cDNA for ABP-2, and the protein it encoded contained nine Zn fingers and regions rich in alanine, glutamine, serine/threonine, glycine, histidine, and asparagine.