Post-translational modification (PTM) of proteins refers to the chemical modification that occurs after the protein is translated by mRNA, and after the protein synthesis is completed, the chemical structure of the protein molecule is changed through a series of biochemical reactions to adjust its function, stability, location or interaction. These modifications can occur on amino acid residues or on the overall structure of the protein. Here are some common forms of protein post-translational modifications:
Figure 1Schematic diagram of the identification of protein post-translational modifications.
1. Phosphorylation: This is one of the most common forms of post-translational modification, usually occurring on serine, threonine, or tyrosine residues. Phosphorylation regulates the activity of many proteins. Involves the addition of phosphate groups to specific amino acid residues such as serine, threonine, and tyrosine. Phosphorylation can regulate the activity, affinity, and stability of proteins.
2. Ubiquitination: It involves binding ubiquitin proteins to target proteins, usually the labeled proteins being degraded.
3. Acetylation: It usually occurs on the N-terminal or lysine residue of the protein, affecting the binding of the protein to DNA or the activity of the protein.
4. Methylation: methylation of methyl groups such as lysine is added to certain amino acid residues. This modification can affect the interaction of certain proteins with DNA or other proteins.
5. Glycosylation: Adding sugar chains to proteins is essential for the stability of proteins and their localization in cells.
6. Palmitoylation: involves attaching fatty acids to proteins, usually related to the localization of proteins on cell membranes.
7. Carboxy-terminal cleavage and acylation: After the protein translation is completed, one or several amino acids may be excised, or acylation modification may be carried out at the carboxyl terminus.
8. Structural modification: such as the formation of disulfide bonds, it is very important for the three-dimensional structural stability of proteins.