What is the cap of mRNA?
The mRNA cap is a methylated modification of the 5′ terminus of mRNA. RNA processing and translation factors are recruited to the mRNA cap. The mRNA cap protects transcripts from degradation and defines mRNA as “self”. Formation of the mRNA cap is regulated by cellular signalling pathways.
Why is 5cap important?
The 5′ cap protects the nascent mRNA from degradation and assists in ribosome binding during translation. The poly (A) tail protects the mRNA from degradation, aids in the export of the mature mRNA to the cytoplasm, and is involved in binding proteins involved in initiating translation.
What enzyme adds the cap to mRNA?
Capping is a three-step process that utilizes the enzymes RNA triphosphatase, guanylyltransferase, and methyltransferase. Through a series of three steps, the cap is added to the first nucleotide’s 5′ hydroxyl group of the growing mRNA strand while transcription is still occurring.
What is m7G?
The m7G cap, also known as cap 0 structure, is essential for the majority of protein translation in vivo. The m7G cap also protects the mature mRNA from degradation, allows for a regulated degradation mechanism, enhances pre-RNA splicing and directs nuclear export.
Does mRNA have a cap?
All eukaryotic mRNA contains a cap structure – an N7-methylated guanosine linked to the first nucleotide of the RNA via a reverse 5′ to 5′ triphosphate linkage (Figure 1).
What is the 5 cap of mRNA?
The 5′ cap is added to the first nucleotide in the transcript during transcription. The cap is a modified guanine (G) nucleotide, and it protects the transcript from being broken down. It also helps the ribosome attach to the mRNA and start reading it to make a protein.
What are two functions of the 5 cap?
The 5′ cap has four main functions:
- Regulation of nuclear export;
- Prevention of degradation by exonucleases;
- Promotion of translation (see ribosome and translation);
- Promotion of 5′ proximal intron excision.
What enzyme adds the 5 cap?
enzyme guanyl transferase
5′ End Capping The cap is added by the enzyme guanyl transferase. This enzyme catalyzes the reaction between the 5′ end of the RNA transcript and a guanine triphosphate (GTP) molecule.
What does mRNA Capping do?
In the eukaryotic cell, capping of mRNA 5′ ends is an essential structural modification that allows efficient mRNA translation, directs pre-mRNA splicing and mRNA export from the nucleus, limits mRNA degradation by cellular 5′–3′ exonucleases and allows recognition of foreign RNAs (including viral transcripts) as ‘non- …
Where does capping occur in mRNA?
mRNA capping in eukaryotes Capping is the first modification made to RNA polymerase II-transcribed RNA and takes place co-transcriptionally in the nucleus as soon as the first 25–30 nts are incorporated into the nascent transcript (6,7).