Question

The addition of a ubiquitin group to a protein does what?

a) Activates the protein
b) Targets the protein for degradation
c) Increases protein synthesis
d) Inhibits protein folding

Answer 1

The addition of a ubiquitin group to a protein signals that the protein should be degraded. This process is integral to controlling gene expression by managing the lifespan of proteins within the cell.

Step-by-step explanation:

The addition of a ubiquitin group to a protein specifically targets the protein for degradation. Ubiquitin serves as a signal, somewhat like a regulatory flag, indicating that the protein's lifecycle has come to an end and it is now time for it to be broken down. After a protein is tagged with ubiquitin, it is then relocated to the proteasome, which is a specialized organelle responsible for degrading proteins. This process plays a critical role in controlling gene expression by altering the longevity of proteins within the cell.