Protein acetylation is a biochemical process where an acetyl group is added to a protein, typically at the amino acid lysine residues. This modification can influence the protein's function, stability, and interactions with other molecules. It plays a crucial role in various cellular processes, including gene expression and metabolism. The process is catalyzed by enzymes known as acetyltransferases, while deacetylases remove the acetyl groups. Protein acetylation is essential for regulating cellular activities and is involved in numerous biological functions, such as cell signaling and the response to stress.