Working with a gene that plays a critical role in HIV infection, University of Maryland researchers have discovered that some human genes have an alternate set of operating instructions written into their protein-making machinery. The alternate instructions can quickly alter the proteins’ contents, functions and ability to survive.
Ribosomes read messenger RNA (mRNA) three nucleotides at a time. But every once in a while it stutters, skips one nucleotide, before starting again.
This causes a frameshift usually resulting in nonsense, producing proteins that are not useful. The protein and the mRNA are then rapidly degraded and things start over again.
So what these researchers found is that the cell actually has a system that directly causes frameshifts, actually controlling protein production by creating nonsense.
How it does this is by using another small RNA – a microRNA or miRNA – that sticks to the mRNA and causes a frameshift at a specific location. The mRNA and resulting proteirn are then targeted for rapid degradation.
So this serves as a negative control loop, decreasing the amount of a specific protein in a cell.
Just another control mechanism in a cell – purposefully inserting errors.