Heterogeneous nuclear ribonucleoprotein A1 and UP1 protect mammalian telomeric repeats and modulate telomere replication in vitro - PubMed (original) (raw)

. 2000 May 12;275(19):14509-16.

doi: 10.1074/jbc.275.19.14509.

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Heterogeneous nuclear ribonucleoprotein A1 and UP1 protect mammalian telomeric repeats and modulate telomere replication in vitro

F Dallaire et al. J Biol Chem. 2000.

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Abstract

The heterogeneous nuclear ribonucleoprotein A1 protein and a shortened derivative (UP1) promote telomere elongation in mammalian cells. To gain insights into the function of A1/UP1 in telomere biogenesis, we have investigated the binding properties of recombinant A1/UP1 and derivatives to single-stranded DNA oligonucleotides. Our results indicate that UP1 prefers to bind to DNA carrying single-stranded telomeric extensions at the 3' terminus. The RNA recognition motif 1 is sufficient for strong and specific binding to oligomers carrying vertebrate telomeric repeats. We find that the binding of A1/UP1 protects telomeric sequences against degradation by endo- and exonucleases. Moreover, A1/UP1 binding prevents extension by telomerase and terminal deoxynucleotidyltransferase and inhibits rNTP-dependent DNA synthesis in vitro. These observations are consistent with the hypothesis that A1/UP1 is a telomere end-binding protein that plays a role in the maintenance of long 3' overhangs.

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