Phosphorylation is a common post-translational modification that involves the addition of a phosphate group to a protein molecule. This modification plays a crucial role in regulating various cellular processes, including cell signaling, metabolism, and gene expression. Phosphorylation is carried out by enzymes called kinases, which transfer a phosphate group from ATP to specific amino acid residues on target proteins. This modification can lead to changes in protein structure, activity, stability, and interactions with other molecules, thereby influencing cell function and behavior. Studying phosphorylation is important for understanding the underlying mechanisms of disease and developing targeted therapies for various conditions.