The HeLa Pur factor binds single-stranded DNA at a specific element conserved in gene flanking regions and origins of DNA replication.
A major site of DNA bending is located 1.6 kb upstream of the P1 transcription start site of the human c-myc gene, near the center of a reported zone of initiation of DNA replication. A repeated, purine-rich element, termed PUR, at the bend site is specifically bound by a protein in HeLa cell nuclear extracts. This protein has specific affinity for the purine-rich single strand of the element. Methylation interference maps a pattern of specific contact points with guanosine bases in a 24-mer oligonucleotide containing the element. UV cross-linking reveals that contact is made by a polypeptide of approximately 28 kDa. The PUR element is present at origins of replication and in gene flanking regions in a variety of eukaryotes from yeasts through humans. The consensus sequence GGNNGAGGGAGARRRR has been derived. This element is present near centers of regions of two mammalian loci (human c-myc and hamster dhfr) recently reported as initiation zones for DNA replication. A 24-mer oligonucleotide representing the hamster dhfr version of the PUR element effectively competes with the human c-myc version for binding to Pur.
Bergemann
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Department of Pathology, Mount Sinai School of Medicine, New York, New York 10029.
Johnson
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D000818:Animals; D001483:Base Sequence; D004252:DNA Mutational Analysis; D004261:DNA Replication / Q000235:genetics*; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000528:radiation effects; D004591:Electrophoresis, Polyacrylamide Gel; D016259:Genes, myc; D006151:Guanosine / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D008745:Methylation; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D014157:Transcription Factors; D014466:Ultraviolet Rays
D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C501130:PURA protein, human; D014157:Transcription Factors; D006151:Guanosine