What are common post-translational modifications and their functions?

Post-translational modifications (PTMs) regulate protein function after synthesis. Phosphorylation (by kinases) is the most common, regulating enzyme activity and signaling. Glycosylation adds carbohydrates affecting folding, stability, and recognition. Ubiquitination tags proteins for proteasomal degradation or alters localization and activity. Acetylation regulates histones and metabolic enzymes. Methylation affects protein-protein interactions and gene regulation. SUMOylation alters protein localization and function. Lipidation (myristoylation, palmitoylation, prenylation) anchors proteins to membranes. PTMs expand functional diversity beyond genetic coding capacity.