"Cap methyltransferase selective binding and methylation of GpppG-RNA are stimulated by importin-alpha."

Wen Y, Shatkin AJ



Published 2000-12-01 in Genes Dev volume 14 .

Pubmed ID: 11114884
DOI identifier: -

Abstract:
We screened a human cDNA library for proteins that bind mRNA cap methyltransferase (MT) and isolated nuclear transporter importin-alpha (Impalpha). This direct association was confirmed by glutathione S-transferase (GST) pulldown, coimmunoprecipitation, and nuclear colocalization. In gel shift assays, MT selectively bound RNA containing 5'-terminal GpppG, and binding was inhibited by GpppG and not by m(7)GpppC. Impalpha markedly enhanced MT binding to GpppG-RNA and stimulated MT activity. MT/RNA/Impalpha complexes were dissociated by importin-beta, which also blocked the stimulation of cap methylation by Impalpha. The presence of RanGTP but not RanGDP prevented these effects of importin-beta. These findings indicate that importins play a novel role in mRNA biogenesis at the level of cap methylation.


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Last modification of this entry: Sept. 6, 2012