title: Genomic structure of the Xenopus laevis liver transcription factor LFB1.
abstract: Liver factor B1 [LFB1, also called hepatocyte nuclear factor 1 (HNF1)] is a tissue-specific vertebrate transcription factor that is present in the liver, intestine, stomach and kidney. The LFB1 protein contains an unusual homeobox that is characterized by an insertion of 21 amino acids (aa) not found in any other homeodomain protein. We have isolated and characterized the genomic sequences encoding the LFB1 of Xenopus laevis. By comparing the genomic sequences with the cDNA clones, we could identify nine exons. In general, the position of the introns is identical to the one previously found in the rat. However, the C-terminal activation domain of LFB1 contains, in each species, an exon that is split in two in the other species. The homeobox of the X. laevis LFB1 contains an intron at exactly the position where the 21 aa typical for LFB1 are inserted. This is in agreement with the structure found in the rat gene and supports the notion that the LFB1 homeobox evolved separately from the other genes encoding homeodomain proteins.
authors.affiliation: Institut für Zellbiologie (Tumorforschung), Universitätsklinikum Essen, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Zapp
authors.forename: S
authors.initials: S
authors.lastname: Bartkowski
authors.forename: C
authors.initials: C
authors.lastname: Zoidl
authors.forename: L
authors.initials: L
authors.lastname: Klein-Hitpass
authors.forename: G U
authors.initials: GU
authors.lastname: Ryffel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004247:DNA; D004268:DNA-Binding Proteins; D005091:Exons; D051537:Hepatocyte Nuclear Factor 1; D051538:Hepatocyte Nuclear Factor 1-alpha; D051539:Hepatocyte Nuclear Factor 1-beta; D007438:Introns; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics*; D029867:Xenopus Proteins; D014982:Xenopus laevis
chemical_list: D004268:DNA-Binding Proteins; D051538:Hepatocyte Nuclear Factor 1-alpha; C000627649:Hnf1b protein, Xenopus; D009687:Nuclear Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins; C496490:hnf1a protein, Xenopus; D051537:Hepatocyte Nuclear Factor 1; D051539:Hepatocyte Nuclear Factor 1-beta; D004247:DNA