Human mRNA cap methyltransferase: alternative nuclear localization signal motifs ensure nuclear localization required for viability.

ABSTRACT: A characteristic feature of gene expression in eukaryotes is the addition of a 5'-terminal 7-methylguanine cap (m7GpppN) to nascent pre-mRNAs in the nucleus catalyzed by capping enzyme and cap methyltransferase. Small interfering RNA (siRNA) knockdown of cap methyltransferase in HeLa cells resulted in apoptosis as measured by terminal deoxynucleotidyltransferase-mediated dUTP-tetramethylrhodamine nick end labeling assay, demonstrating the importance of mRNA 5'-end methylation for mammalian cell viability. Nuclear localization of cap methyltransferase is mediated by interaction with importin-alpha, which facilitates its transport and selective binding to transcripts containing 5'-terminal GpppN. The methyltransferase 96-144 region has been shown to be necessary for importin binding, and N-t

SUBMITTER: Shafer B 

PROVIDER: S-EPMC1061643 | biostudies-literature | 2005 Apr

REPOSITORIES: biostudies-literature