Acetyltransferases are enzymes that facilitate the transfer of an acetyl group from one molecule to another. This process is crucial in various biological reactions, including the modification of proteins and the metabolism of drugs. By adding acetyl groups, these enzymes can alter the function and activity of target molecules, impacting cellular processes. These enzymes play a significant role in gene regulation and cell signaling. For example, in histone acetylation, acetyltransferases modify histone proteins, which can influence DNA accessibility and gene expression. Their activity is essential for maintaining proper cellular functions and responding to environmental changes.