Protein phosphorylation

Phosphorylated serine

Phosporylation of a serine residue, before and after shot

Protein AXL PDB 2c5d

PTM-phosphorylation-example-jepoirrier

Protein phosphorylation is a biochemical process that involves the addition of a phosphate group to a protein molecule. This process is a crucial post-translational modification that regulates the function, activity, and interaction of proteins within the cell.

Mechanism

Protein phosphorylation is typically catalyzed by enzymes known as protein kinases. These enzymes transfer a phosphate group from a high-energy molecule, such as adenosine triphosphate (ATP), to specific amino acid residues in the target protein. The most common residues that undergo phosphorylation are serine, threonine, and tyrosine.

Function

Phosphorylation plays a key role in various cellular processes, including:

• Signal transduction: Phosphorylation acts as a molecular switch that can turn on or off the activity of proteins involved in signaling pathways.
• Cell cycle regulation: Phosphorylation controls the progression of cells through the cell cycle by regulating the activity of cyclin-dependent kinases (CDKs).
• Metabolism: Enzymes involved in metabolic pathways are often regulated by phosphorylation, which can alter their activity and thus the metabolic flux.
• Apoptosis: Phosphorylation can either promote or inhibit programmed cell death, depending on the context and the specific proteins involved.

Dephosphorylation

The removal of phosphate groups from proteins, known as dephosphorylation, is carried out by enzymes called protein phosphatases. This process is equally important as phosphorylation and ensures that the phosphorylation state of proteins is tightly regulated.

Clinical Significance

Abnormal protein phosphorylation is associated with various diseases, including cancer, diabetes, and neurodegenerative disorders. For instance, overactive kinases can lead to uncontrolled cell proliferation in cancer, while impaired phosphorylation of insulin receptors is a hallmark of diabetes.

Related Pages

• Protein kinase
• Protein phosphatase
• Signal transduction
• Cell cycle
• Apoptosis
• Enzyme regulation

See Also

• Post-translational modification
• Adenosine triphosphate
• Serine
• Threonine
• Tyrosine