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RAM function is dependent on Kapβ2-mediated nuclear entry

Eukaryotic gene expression is dependent on the modification of the first transcribed nucleotide of pre-mRNA by the addition of the 7-methylguanosine cap. The cap protects transcripts from exonucleases and recruits complexes which mediate transcription elongation, processing and translation initiatio...

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Autores principales: Gonatopoulos-Pournatzis, Thomas, Cowling, Victoria H.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Portland Press Ltd. 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3898117/
https://www.ncbi.nlm.nih.gov/pubmed/24200467
http://dx.doi.org/10.1042/BJ20131359
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author Gonatopoulos-Pournatzis, Thomas
Cowling, Victoria H.
author_facet Gonatopoulos-Pournatzis, Thomas
Cowling, Victoria H.
author_sort Gonatopoulos-Pournatzis, Thomas
collection PubMed
description Eukaryotic gene expression is dependent on the modification of the first transcribed nucleotide of pre-mRNA by the addition of the 7-methylguanosine cap. The cap protects transcripts from exonucleases and recruits complexes which mediate transcription elongation, processing and translation initiation. The cap is synthesized by a series of reactions which link 7-methylguanosine to the first transcribed nucleotide via a 5′ to 5′ triphosphate bridge. In mammals, cap synthesis is catalysed by the sequential action of RNGTT (RNA guanylyltransferase and 5′-phosphatase) and RNMT (RNA guanine-7 methyltransferase), enzymes recruited to RNA pol II (polymerase II) during the early stages of transcription. We recently discovered that the mammalian cap methyltransferase is a heterodimer consisting of RNMT and the RNMT-activating subunit RAM (RNMT-activating mini-protein). RAM activates and stabilizes RNMT and thus is critical for cellular cap methylation and cell viability. In the present study we report that RNMT interacts with the N-terminal 45 amino acids of RAM, a domain necessary and sufficient for maximal RNMT activation. In contrast, smaller components of this RAM domain are sufficient to stabilize RNMT. RAM functions in the nucleus and we report that nuclear import of RAM is dependent on PY nuclear localization signals and Kapβ2 (karyopherin β2) nuclear transport protein.
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spelling pubmed-38981172014-01-23 RAM function is dependent on Kapβ2-mediated nuclear entry Gonatopoulos-Pournatzis, Thomas Cowling, Victoria H. Biochem J Research Article Eukaryotic gene expression is dependent on the modification of the first transcribed nucleotide of pre-mRNA by the addition of the 7-methylguanosine cap. The cap protects transcripts from exonucleases and recruits complexes which mediate transcription elongation, processing and translation initiation. The cap is synthesized by a series of reactions which link 7-methylguanosine to the first transcribed nucleotide via a 5′ to 5′ triphosphate bridge. In mammals, cap synthesis is catalysed by the sequential action of RNGTT (RNA guanylyltransferase and 5′-phosphatase) and RNMT (RNA guanine-7 methyltransferase), enzymes recruited to RNA pol II (polymerase II) during the early stages of transcription. We recently discovered that the mammalian cap methyltransferase is a heterodimer consisting of RNMT and the RNMT-activating subunit RAM (RNMT-activating mini-protein). RAM activates and stabilizes RNMT and thus is critical for cellular cap methylation and cell viability. In the present study we report that RNMT interacts with the N-terminal 45 amino acids of RAM, a domain necessary and sufficient for maximal RNMT activation. In contrast, smaller components of this RAM domain are sufficient to stabilize RNMT. RAM functions in the nucleus and we report that nuclear import of RAM is dependent on PY nuclear localization signals and Kapβ2 (karyopherin β2) nuclear transport protein. Portland Press Ltd. 2014-01-10 2014-02-01 /pmc/articles/PMC3898117/ /pubmed/24200467 http://dx.doi.org/10.1042/BJ20131359 Text en © 2014 The author(s) has paid for this article to be freely available under the terms of the Creative Commons Attribution Licence (CC-BY)(http://creativecommons.org/licenses/by/3.0/) which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited. http://creativecommons.org/licenses/by/3.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Article
Gonatopoulos-Pournatzis, Thomas
Cowling, Victoria H.
RAM function is dependent on Kapβ2-mediated nuclear entry
title RAM function is dependent on Kapβ2-mediated nuclear entry
title_full RAM function is dependent on Kapβ2-mediated nuclear entry
title_fullStr RAM function is dependent on Kapβ2-mediated nuclear entry
title_full_unstemmed RAM function is dependent on Kapβ2-mediated nuclear entry
title_short RAM function is dependent on Kapβ2-mediated nuclear entry
title_sort ram function is dependent on kapβ2-mediated nuclear entry
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3898117/
https://www.ncbi.nlm.nih.gov/pubmed/24200467
http://dx.doi.org/10.1042/BJ20131359
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