Non-AUG translation initiation in mammals

Area of Science:

• Molecular Biology
• Proteomics
• Genomics

Background:

• Proteogenomic studies show translation occurs beyond annotated protein-coding regions.
• Non-canonical translation originates from untranslated regions (UTRs) and non-coding RNAs.
• Start codon plurality within a single RNA molecule drives this phenomenon.

Purpose of the Study:

• To discuss the current understanding of non-AUG initiation.
• To highlight the role of leaky scanning in non-canonical translation.
• To propose a ubiquitous role for non-AUG initiation in mammalian proteome dynamics.

Main Methods:

• Review of recent proteogenomic findings.
• Analysis of ribosome scanning and initiation mechanisms.
• Discussion of start codon plurality and leaky scanning.

Main Results:

• Extensive translation occurs outside of annotated protein-coding regions.
• Leaky scanning, the failure of ribosomes to recognize upstream start codons, leads to downstream initiation.
• Non-AUG codons are inefficient and contribute significantly to leaky scanning.

Conclusions:

• Non-AUG initiation is a widespread mechanism in mammals.
• This process significantly contributes to the dynamic composition of the proteome.
• Understanding non-AUG initiation is crucial for a complete view of protein synthesis.