Post-translational modifications (PTMs) are chemical changes that occur to proteins after they have been synthesized by ribosomes. These modifications can include the addition of functional groups, such as phosphate or carbohydrate molecules, which can alter a protein's function, stability, or location within a cell. PTMs play a crucial role in regulating various biological processes, including cell signaling, metabolism, and gene expression. Common types of PTMs include phosphorylation, glycosylation, and ubiquitination. Each of these modifications can significantly impact how proteins interact with other molecules and perform their roles in the body. Understanding PTMs is essential for studying diseases and developing targeted therapies, as many conditions arise from dysregulation of these processes.