RNMT (RNA (guanine-7-) methyltransferase) is a widely expressed nuclear protein that belongs to the mRNA cap methyltransferase family. It is responsible for catalyzing the final step in the attachment of the m7GpppN cap to the 5' end of mRNA. Capping of mRNA plays an important role in mRNA processing, stability and translation and is therefore important for efficient gene expression. There are three enzymatic steps in the generation of the mRNA cap. The first two steps are catalyzed by RNGTT (RNA guanylyltransferase and 5' phosphatase), and the third step is catalyzed by RNMT. More specifically, RNMT catalyzes the transfer of a methyl group from AdoMet (S-adenosylmethionine) to the GpppN end of the growing mRNA at the N-7 position, thereby producing AdoHyc (S-adenosylhomocysteine) and m7GpppN terminated RNA. Two additional isoforms of RNMT exist due to alternative splicing events, namely hCMT1a and hCMT1b.
Function:
mRNA-capping methyltransferase that methylates the N7 position of the added guanosine to the 5'-cap structure of mRNAs. Binds RNA containing 5'-terminal GpppC.
Subunit:
Interacts with importin alpha, leading to stimulate both RNA-binding and methyltransferase activity. Interaction with importin alpha and beta is required for its nuclear localization, importin beta dissociating in response to RanGTP, allowing RNMT-importin alpha to bind RNA substrates. Interacts with elongating form of polymerase II and RNGTT. Interacts with RAM/FAM103A1, the interaction significantly enhances RNA-binding and cap methyltransferase activity.
Subcellular Location:
Nucleus.
Tissue Specificity:
Widely expressed.
Similarity:
Belongs to the class I-like SAM-binding methyltransferase superfamily. mRNA cap 0 methyltransferase family.
Contains 1 mRNA cap 0 methyltransferase domain.
SWISS:
O43148
Gene ID:
8731
Database links:
Entrez Gene: 8731 Human
Omim: 603514 Human
SwissProt: O43148 Human
Unigene: 592347 Human
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