What can occur when start and stop locations for translation are poorly defined?

When start and stop locations for translation are poorly defined, the primary issue that arises is a frameshift mutation. A frameshift mutation occurs when the reading frame of the mRNA is altered due to the improper recognition of the start codon or stop codon. This misalignment results in a shift in the way the ribosome reads the sequence of nucleotides during translation. Consequently, the entire downstream sequence is translated incorrectly, leading to the production of a completely different set of amino acids.

This can have severe implications for the resulting protein, often rendering it nonfunctional or causing it to have a completely altered function. Whereas gene expression, protein folding, and amino acid sequencing errors can all be impacted by translation inaccuracies, the specific consequence of poorly defined start and stop locations aligns directly with the concept of a frameshift mutation, which fundamentally disrupts the reading frame of the mRNA and alters the downstream amino acid sequence.