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#mRNA capping

2 public questions tagged with this topic.

Translation in Prokaryotes and Eukaryotes

Cap binding protein in eukaryotes is

Cap-binding protein in eukaryotic cytosolic translation is eIF4E, 24 kDa subunit of eIF4F complex also containing scaffold eIF4G and helicase eIF4A. eIF4E specifically binds 7-methylguanosine cap structure at 5' end of mRNA via aromatic stacking interactions with tryptophan residues, recruiting mRNA to 43S pre-initiation complex for scanning. Activity controlled by binding proteins 4E-BPs that sequester eIF4E under nutrient deprivation, phosphorylation influencing affinity, and availability limiting translation of oncogenic growth factor mRNAs characterized by complex 5' UTRs requiring helicas

Ref: Watson Molecular Biology of the Gene, 7th ed., Chapter 15, eIF4E cap-binding protein recognizing m7G cap

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Processing of mRNA, rRNA, tRNA

5' capping of mRNA occurs in

Five prime capping of messenger RNA occurs predominantly in nucleus, co-transcriptionally while polymerase II remains bound to DNA template. Capping enzymes RNA triphosphatase, guanylyltransferase, and methyltransferase are recruited to promoter-proximal polymerase via binding to Serine five phosphorylated C-terminal domain. Enzymatic addition of 7-methylguanosine via five prime to five prime triphosphate linkage happens within first minutes of transcription when nascent RNA emerges. Resulting cap binding complex CBP20 and CBP80 protects transcript from nuclear exonucleases, facilitates splici

Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter 10: 5' capping occurs in nucleus cotranscriptionally; Alberts et al., Nuclear processing compartments

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