Post Translational Modification- Definition, Processing


Proteins are the workhorses of the cell, performing a variety of functions such as catalysis, transport, signaling, and regulation. However, proteins are not always ready to function right after they are synthesized by ribosomes. Many proteins undergo further changes after translation, which are collectively called post-translational modifications (PTMs).

PTMs are covalent and usually enzymatic alterations of amino acid side chains or protein termini that occur after the protein has been translated from mRNA. PTMs can modify the chemical properties, conformation, stability, interactions, and localization of proteins, thereby affecting their activity and function. PTMs can also create new functional groups or binding sites on proteins that are not encoded by the genetic code.

There are more than 400 different types of PTMs that have been identified in various organisms, ranging from bacteria to humans. Some of the most common and well-studied PTMs include proteolysis, phosphorylation, glycosylation, sulfation, methylation, hydroxylation, acetylation, ubiquitination, and SUMOylation. These modifications can occur on specific amino acids or protein termini, depending on the enzymes and cofactors involved.

PTMs are essential for many cellular processes and biological functions. They can regulate protein folding, stability, degradation, trafficking, localization, and interactions. They can also modulate enzyme activity, signal transduction pathways, gene expression, chromatin structure, DNA repair, cell cycle progression, and cell death. Dysregulation or malfunction of PTMs can lead to various diseases such as cancer, diabetes, neurodegeneration, and immune disorders.

Therefore, understanding the mechanisms and functions of PTMs is crucial for advancing our knowledge of protein biology and human health. In this article, we will review some of the major types of PTMs and their roles in protein processing and function. We will also discuss some of the tools and methods for identifying and predicting PTMs in proteins.