postranslational

Postranslational refers to events that occur after a protein has been synthesized from messenger RNA (mRNA) through the process of translation. While translation is the fundamental step of creating a polypeptide chain, postranslational modifications are crucial for a protein to achieve its final functional form, stability, and cellular localization. These modifications are diverse and can significantly alter a protein's properties.

Common postranslational modifications include the addition of various chemical groups such as phosphates (phosphorylation), sugars (glycosylation), lipids (lipidation), or acetyl groups (acetylation). These modifications can act as molecular switches, turning protein activity on or off, or can influence protein-protein interactions, protein folding, and protein degradation. Proteolytic cleavage, the cutting of a polypeptide chain into smaller fragments, is another critical postranslational event that can activate or inactivate proteins.

Other modifications involve the formation of disulfide bonds, which are essential for the proper three-dimensional structure of many secreted and transmembrane proteins. The addition of cofactors or metal ions can also be considered postranslational. These modifications are not random; they are often carried out by specific enzymes and occur in designated cellular compartments, such as the endoplasmic reticulum or Golgi apparatus, ensuring that proteins are correctly modified before reaching their final destination and performing their intended functions within the cell or organism.