protein phosphorylation

Definition

Target type: biologicalprocess

The process of introducing a phosphate group on to a protein. [GOC:hb]

Protein phosphorylation is a fundamental regulatory mechanism in cellular processes, involving the addition of a phosphate group (PO43−) to a protein. This process is catalyzed by enzymes called kinases, which transfer the phosphate group from a donor molecule, typically ATP, to specific amino acid residues within the target protein. The most common phosphorylation sites are serine, threonine, and tyrosine residues.

Phosphorylation can significantly alter the conformation and activity of a protein. It can:

* **Activate** a protein, turning it "on" and allowing it to perform its function.
* **Inactivate** a protein, turning it "off" and preventing its function.
* **Change the protein's localization** within the cell.
* **Modify its interaction with other proteins.**

This reversible process allows cells to fine-tune their responses to a wide range of stimuli, including growth factors, hormones, and stress.

The process of protein phosphorylation occurs in several steps:

1. **Kinase binding:** The kinase binds to the target protein, recognizing specific amino acid sequences surrounding the phosphorylation site.
2. **Phosphate transfer:** The kinase catalyzes the transfer of a phosphate group from ATP to the hydroxyl group of the target amino acid residue.
3. **Conformational change:** The addition of the phosphate group alters the protein's conformation, often changing its activity.

The phosphorylation state of a protein is tightly regulated by the opposing actions of kinases and phosphatases. Phosphatases are enzymes that remove phosphate groups from proteins, effectively reversing the phosphorylation process.

The interplay between kinases and phosphatases creates a dynamic and complex regulatory network that controls a vast array of cellular processes, including:

* **Signal transduction:** Phosphorylation is a key component of signaling pathways that relay information from the environment to the cell's interior, influencing gene expression, cell growth, and metabolism.
* **Cell cycle control:** Phosphorylation events regulate the progression of the cell cycle, ensuring proper DNA replication and cell division.
* **DNA repair:** Phosphorylation plays a crucial role in DNA damage recognition and repair mechanisms.
* **Metabolic regulation:** Phosphorylation controls enzyme activity in metabolic pathways, regulating the production and utilization of energy.

Dysregulation of protein phosphorylation can lead to various diseases, including cancer, diabetes, and neurological disorders. Understanding the mechanisms of phosphorylation is crucial for developing targeted therapies for these conditions.'
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Proteins (334)

Compounds (1,528)