Cytosine-block telomeric type DNA-binding activity of hnRNP proteins from human cell lines |
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Authors: | Bandiera Antonella Tell Gianluca Marsich Eleonora Scaloni Andrea Pocsfalvi Gabriella Akintunde Akindahunsi A Cesaratto Laura Manzini Giorgio |
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Affiliation: | Department of Biochemistry, Biophysics, and Macromolecular Chemistry, University of Trieste, via L. Giorgieri 1, 34127, Trieste, Italy. |
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Abstract: | Following the observation of the presence in mammalian nuclear extracts of a DNA binding activity quite specific for the single-stranded C-rich telomeric motif, we have isolated from the K562 human cell line by affinity chromatography and identified by mass spectrometry a number of proteins able to bind to this sequence. All of them belong to different heterogeneous nuclear ribonucleoprotein subgroups (hnRNP). Whereas many of them, namely hnRNP K, two isoforms of hnRNP I, and the factor JKTBP, appear to bind to this sequence with limited specificity after isolation, an isoform of hnRNP D (alias AUF1) and particularly hnRNP E1 (alias PCBP-1) show a remarkable specificity for the (CCCTAA)n repeated motif. Both have been obtained also as recombinant proteins expressed in Escherichia coli and have been shown to retain their binding specificity toward the C-block repeated sequence. In the light of the current knowledge about these proteins, their possible involvement in telomere functioning is discussed. |
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Keywords: | hnRNPs C-rich repeated motif Telomere Single-stranded DNA |
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