The Xenopus B1 factor is closely related to the mammalian activator USF and is implicated in the developmental regulation of TFIIIA gene expression.
The Xenopus laevis TFIIIA promoter contains a motif that has been implicated in promoter activation in late-stage oocytes and contains the sequence (-269) CACGTG (-264). A cDNA encoding a protein (B1) that binds to this element has been cloned from X. laevis and Xenopus borealis ovarian cDNA libraries. We show that this protein is a member of the helix-loop-helix family of regulatory proteins and contains 80% sequence identity with the human adenovirus major late transcription factor (MLTF or USF). A survey of B1 protein expression during oogenesis and embryogenesis revealed both oocyte-specific and somatic cell-specific B1 protein-DNA complexes. Immunological data, RNA blot analysis, and proteolytic clipping band shift assays indicated that these complexes most likely represent altered forms of a single B1 polypeptide. Implications for TFIIIA gene regulation during development are discussed.
Kaulen
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Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, New York 10021-6399.
Pognonec
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Gregor
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Roeder
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D005786:Gene Expression Regulation; D005796:Genes; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000737:chemistry; D009865:Oocytes / Q000502:physiology; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D035582:Transcription Factor TFIIIA; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology*; D051720:Upstream Stimulatory Factors; D014981:Xenopus / Q000235:genetics; D014982:Xenopus laevis / Q000196:embryology / Q000502:physiology*
C066779:B1 factor, Xenopus; D004268:DNA-Binding Proteins; D009841:Oligonucleotides; D012333:RNA, Messenger; D035582:Transcription Factor TFIIIA; D014157:Transcription Factors; D051720:Upstream Stimulatory Factors; D004247:DNA