BAP, a rat liver protein that activates transcription through a promoter element with similarity to the USF/MLTF binding site.
The vitellogenin genes of Xenopus are liver-specifically expressed. An in vitro transcription system derived from rat liver nuclei allowed us to define the cis-element BABS (B-activator binding site) in the promoter of the B1 vitellogenin gene. An oligonucleotide encompassing the region from -53 to -44 linked to a TATA box is sufficient for a tenfold increase of the transcriptional activity. Gel retardation assays with nuclear rat liver proteins reveal two DNA-protein complexes: Complex 1 can be competed by the USF/MLTF binding site of the adeno major late promoter whereas complex 2 is a distinct protein we refer to as BAP (B-activator protein). In vitro transcription experiments in the presence of USF/MLTF binding site as competitor show that BAP is an efficient transcription factor. Based on UV cross-linking we estimate that BAP has a molecular weight of 58 kd. Phosphatase treatment reveals that DNA binding of BAP requires phosphorylation. BABS is also present in the hepatitis B virus enhancer suggesting that it might play a role in the tumorigenic potential of the virus.
Kugler
W
W
Kernforschungszentrum Karlsruhe, Institut für Genetik und Toxikologie, Karlsruhe, FRG.
Kaling
M
M
Ross
K
K
Wagner
U
U
Ryffel
G U
GU
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D004252:DNA Mutational Analysis; D005786:Gene Expression Regulation; D008099:Liver / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D051381:Rats; D011919:Rats, Inbred Strains; D016385:TATA Box; D014157:Transcription Factors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014158:Transcription, Genetic; D014819:Vitellogenins / Q000235:genetics
D014157:Transcription Factors; D014819:Vitellogenins; D010744:Phosphoric Monoester Hydrolases