Post-Translational Modifications: Key to Regulating Bioactivity

Post-translational modification (PTM) refers to the chemical modifications that occur after a protein is translated from mRNA. After protein synthesis is completed, the chemical structure of the protein molecule is altered through a series of biochemical reactions to regulate its functionality, stability, location, or interactions. 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:

 

Phosphorylation

This is one of the most common forms of post-translational modification, usually occurring on serine, threonine, or tyrosine residues. Phosphorylation plays a regulatory role in the activity of many proteins. It 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.

 

Ubiquitination

This involves the combination of ubiquitin protein with the target protein, usually marking the protein for degradation.

 

Acetylation

This usually occurs at the N-terminus of the protein or on lysine residues, affecting the binding of the protein to DNA or the activity of the protein.

 

Methylation

This involves the addition of methyl groups to certain amino acid residues, such as methylation of lysine. This modification can affect the interaction of certain proteins with DNA or other proteins.

 

Glycosylation

This involves the addition of sugar chains to proteins, which is crucial for the stability of proteins and their localization within cells.

 

Palmitoylation

This involves attaching fatty acids to proteins, usually related to the localization of proteins on the cell membrane.

 

Carboxy-Terminal Cleavage and Acylation

After protein translation is completed, one or several amino acids may be cleaved, or acylation modifications may be made at the carboxy terminus.

 

Structural Modifications

Such as the formation of disulfide bonds, which are very important for the stability of the protein's three-dimensional structure.