Human CDC45 protein binds to minichromosome maintenance 7 protein and the p70 subunit of DNA polymerase alpha.
Budding yeast CDC45 encodes Cdc45p, an essential protein required to trigger initiation of DNA replication in late G1 phase. We cloned four and one species of the human Cdc45p homolog cDNA, resulting from different splicing patterns, from HeLa cell and human placenta cDNA libraries, respectively. A comparison of the cDNAs and the genomic sequence showed that the longest encoding a 610-amino acid protein was comprised of 20 exons. One species, which lacks exon 7 and contains the shorter of two exons 18, was identical with the previously reported CDC45L cDNA and constituted 24 out of 28 clones from HeLa cells. Splicing was different in HeLa cells and TIG-1 cells, a human diploid cell line. Human CDC45 protein was found to bind directly in vitro to human minichromosome maintenance 7 protein (hMCM7) and to the p70 subunit of DNA polymerase alpha. The data support a thesis that human CDC45 acts as a molecular tether to mediate loading of the DNA polymerase alpha on to the DNA replication complex through binding to hMCM7.
Kukimoto
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Division of Molecular Genetics, National Institute of Infectious Diseases, Tokyo, Japan. ikuki@nih.go.jp
Igaki
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Kanda
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D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D003001:Cloning, Molecular; D004256:DNA Polymerase I / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D066298:In Vitro Techniques; D064168:Minichromosome Maintenance Complex Component 7; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D014764:Viral Proteins / Q000235:genetics
C102209:CDC45 protein, S cerevisiae; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014764:Viral Proteins; D004256:DNA Polymerase I; C491088:MCM7 protein, S cerevisiae; C101624:MCM7 protein, human; D064168:Minichromosome Maintenance Complex Component 7