2.5 Summary of Section 2
A newly synthesised polypeptide can undergo a number of modifications and adjustments before it has the structure and activity of a mature functional protein. Some proteins require non-protein components, termed cofactors, for their function.
A newly synthesised polypeptide undergoes rapid initial folding. Fine-tuning of the conformation is much slower and is often facilitated by specialised proteins called chaperones.
Covalent modifications of proteins include glycosylation, addition of lipid groups, methylation or acetylation, and phosphorylation. Most covalent modifications of proteins occur after translation; however, myristoylation occurs during translation.
Glycosylated proteins are generally destined for secretion or are localised at the extracellular surface of the cell membrane. Lipid modifications serve to anchor proteins in membranes.