Common Post-Translational Modifications of Proteins

Post-translational modification (PTM) refers to the biochemical process where specific amino acid residues of a protein are chemically modified after its translation. These chemical modifications greatly expand the functional diversity of proteins, enabling them to participate in more cellular physiological processes. The following are some common post-translational modifications of proteins:

 

1. Phosphorylation

Phosphorylation is one of the most common post-translational modifications, mainly involving serine, threonine, and tyrosine residues in proteins. This modification is crucial for signal transduction processes.

 

2. Ubiquitination

Involves covalent binding of ubiquitin to the target protein, usually leading to protein degradation by the 26S proteasome.

 

3. Acetylation

Mainly occurs at the N-terminus of proteins or on lysine residues. This modification is especially important in histone modification and transcriptional regulation.

 

4. Methylation

Commonly occurs on lysine and arginine residues, related to gene expression regulation, DNA repair, and RNA processing.

 

5. Glycosylation

According to the structure of the glycan and the glycosylation site, there are mainly two types: N-glycosylation and O-glycosylation. Glycosylation not only affects the spatial conformation, biological activity, transport, and localization of proteins, but also plays a crucial role in specific biological processes such as molecular recognition, cell communication, signal transduction, and others.

 

6. Disulfide Bond

Particularly common in extracellularly secreted proteins, helps proteins fold into the correct three-dimensional structure.

 

7. SUMOylation

SUMOylation involves covalently linking the Small Ubiquitin-like Modifier (SUMO) to specific lysine residues of the target protein. It can influence numerous cellular processes, including but not limited to protein stability, nuclear transport, gene transcription, DNA repair, and cell cycle progression.

 

These are just common types of protein modifications. In reality, protein modifications are very diverse and complex, involving various chemical reactions and structural changes. They collectively determine the function and activity of proteins.