Identification of a protein that recognizes a distal negative regulatory element within the mouse mammary tumor virus long terminal repeat

The mouse mammary tumor virus (MMTV) long terminal repeat contains a distal negative regulatory element (dNRE) that selectively represses activity of the proviral promoter in the absence of steroid hormone receptor-mediated a ctivation. A protein, termed MMTV NRE-binding protein 1 (MNBP-1), that reco gnizes long terminal repeat sequences between -433 and -418 was identified by gel electrophoresis mobility shift assays and methylation interference f ootprinting in nuclear extracts of HeLa and Ltk(-) cells. Mutations within the defined binding site affect dNRE-mediated promoter repression in vivo. MNBP-1 has an apparent molecular mass of approximately 100 kDa as determine d by gel filtration chromatography, (C) 1999 Academic Press.