Question

What is a protein kinase, and what is its role in a signal transduction pathway?

Short answer

Enzymes that phosphorylate proteins using ATP (adenosine triphosphate) as a phosphate source are called protein kinase.

Each protein kinase phosphorylates other protein kinases, activating them in a signal transduction cascade.

Step-by-step solution

Signal Transduction

Signal transduction is the mechanism of transmitting signals from receptors to target molecules within the cell through a sequence of chemical interactions. The process involves the activation of proteins through phosphorylation that acts as signaling molecules.

These activated molecules further activate other proteins or molecules in the pathway that leads to amplification of the molecule.

Explanation for protein kinase

Enzymes are proteins that are the natural catalyst. Protein kinase is one such enzyme that regulates the biological activity of proteins. These enzymes modify other proteins by phosphorylating them.

Protein kinase uses ATP as a phosphate source to add a phosphate group to other proteins, phosphorylating them. The phosphorylation changes the inactive state of protein to an active state, thereby activating them.

Role of protein kinase in signal transduction

Protein kinase is one of the crucial enzymes for signal transduction. The phosphorylation catalyzed by protein kinase forms a phosphorylation cascade. Phosphorylation cascade is a series of reactions in the signaling pathway where one protein kinase phosphorylates another in a series.

Phosphorylated proteins cause the amplification of the signal to create a cellular response. Thus, protein kinase regulates the activities of numerous proteins in the cell. These proteins control the growth and development of the cell.

However, aberrant protein kinase activity can drive cell division and lead to cancer development in cells.