mRNA modification

Definition

Target type: biologicalprocess

The covalent alteration of one or more nucleotides within an mRNA molecule to produce an mRNA molecule with a sequence that differs from that coded genetically. [GOC:curators]

mRNA modification is a crucial process in gene expression, ensuring the stability, translation efficiency, and function of mRNA molecules. This process involves a series of enzymatic modifications that occur co-transcriptionally or post-transcriptionally. These modifications alter the structure and function of mRNA, impacting its fate and ultimately influencing protein production.

**1. Capping**: The 5' end of nascent mRNA transcripts is capped with a 7-methylguanosine (m7G) cap. This modification protects the mRNA from degradation, enhances translation initiation, and facilitates nuclear export.

**2. Splicing**: Non-coding introns are removed from pre-mRNA, while coding exons are joined together to create mature mRNA. This process is catalyzed by the spliceosome, a complex of proteins and small nuclear RNAs (snRNAs). Alternative splicing allows for the generation of multiple protein isoforms from a single gene.

**3. Polyadenylation**: A poly(A) tail is added to the 3' end of mRNA. This tail protects the mRNA from degradation, enhances translation efficiency, and contributes to mRNA stability.

**4. Editing**: Specific nucleotides in mRNA can be modified through editing. This process can alter the coding sequence, introducing amino acid substitutions or creating stop codons.

**5. Methylation**: Methylation of mRNA can occur at various positions, including the 5' cap, the poly(A) tail, and internal sites. These modifications regulate mRNA stability, translation, and localization.

**6. Pseudouridylation**: Pseudouridine (Ψ) is a modified base found in mRNA. This modification can influence mRNA structure, stability, and translation.

**7. Other Modifications**: Several other modifications can occur in mRNA, including adenosine-to-inosine (A-to-I) editing, N6-methyladenosine (m6A) methylation, and N1-methyladenosine (m1A) methylation. These modifications play diverse roles in mRNA metabolism.

**8. Regulation**: The various modifications to mRNA are not random events but are tightly regulated by cellular signals and environmental cues. This regulation ensures proper gene expression and cellular function.'
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Proteins (1)

Compounds (1)