A myosin-like dimerization helix and an extra-large homeodomain are essential elements of the tripartite DNA binding structure of LFB1.
The transcription activator LFB1 is a major determinant of hepatocyte-specific expression of many genes. To study the mechanisms underlying LFB1 transcriptional selectivity, we have initiated its biochemical characterization. By in vitro complementation assays we have defined two distinct regions required for high levels of transcription, which resemble previously described activation domains. In contrast, the region of LFB1 necessary for DNA binding displays several novel features. The DNA binding domain is tripartite, including a homeodomain of unusual length (81 amino acids) and an N-terminal helix similar to part of myosin. This helical region mediates dimerization, which is shown to be essential for DNA binding.
Nicosia
A
A
European Molecular Biology Laboratory, Heidelberg, Federal Republic of Germany.
Monaci
P
P
Tomei
L
L
De Francesco
R
R
Nuzzo
M
M
Stunnenberg
H
H
Cortese
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002872:Chromosome Deletion; D004268:DNA-Binding Proteins; D005816:Genetic Complementation Test; D051537:Hepatocyte Nuclear Factor 1; D051538:Hepatocyte Nuclear Factor 1-alpha; D051539:Hepatocyte Nuclear Factor 1-beta; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009154:Mutation; D009206:Myocardium / Q000378:metabolism; D009218:Myosins / Q000235:genetics*; D009687:Nuclear Proteins; D015345:Oligonucleotide Probes; D010957:Plasmids; D014176:Protein Biosynthesis; D011487:Protein Conformation; D051381:Rats; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D051538:Hepatocyte Nuclear Factor 1-alpha; C496489:Hnf1a protein, rat; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D015345:Oligonucleotide Probes; D014157:Transcription Factors; D051537:Hepatocyte Nuclear Factor 1; D051539:Hepatocyte Nuclear Factor 1-beta; D009218:Myosins