Post-Translational Modification (PTM)
Post-Translational Modification (PTM) refers to the process of modification of one or more amino acids in a protein after it has been translated by the ribosome. Proteins are typically generated by the ribosome, which translates mRNA into a polypeptide chain, which then forms a mature protein product through PTM. PTM plays an important role in regulating protein folding, targeting specific subcellular compartments, interacting with ligands or other proteins, and signal transduction pathways.
PTM can occur on the side chains of amino acids or at the C- or N-terminus of proteins. Phosphorylation is one of the most common PTMs, and its mechanism is related to the regulation of enzyme activity. Glycosylation is a PTM process that exists in many eukaryotic and prokaryotic proteins, where carbohydrate molecules can attach to these proteins, improving protein folding and stability, and regulating protein function. Lipidation is another form of PTM, where lipid molecules are attached to a protein or a part of a protein that is attached to the cell membrane.