What does post-translational modification refer to?

Post-translational modification refers to the chemical alterations that a protein undergoes after its synthesis, or translation, has occurred. Once a protein is synthesized by ribosomes, it can be subjected to a variety of modifications that can affect its function, stability, localization, and interaction with other molecules.

These modifications can include processes such as phosphorylation, glycosylation, ubiquitination, methylation, and acetylation, among others. Each of these alterations can influence the protein’s activity or how it interacts with other cellular components. For instance, phosphorylation can activate or deactivate enzymes, while glycosylation can affect protein folding and stability.

This is distinct from other processes mentioned in the choices, such as mRNA modification, which occurs before translation, or the production of ribosomal RNA, which is a different aspect of cellular machinery. Additionally, protein degradation is a separate process that involves breaking down proteins, rather than modifying them after they are made. Thus, the option regarding the chemical modification of a protein after translation accurately describes the concept and scope of post-translational modifications in protein biology.