The activation of receptor tyrosine kinases is characterized by a. dimerization and phosphorylation. b. dimerization and IP3 binding. c. a phosphorylation cascade. d. GTP hydrolysis.

Verified step by step guidance

1. Understand the function of receptor tyrosine kinases (RTKs): RTKs are a class of enzymes that are key regulators of cellular processes. They are activated by the binding of a ligand (such as a growth factor) to the receptor's extracellular domain.
2. Recognize the process of dimerization: Upon ligand binding, RTKs undergo dimerization, which means two RTK molecules pair up. This dimerization is crucial for the next step in their activation.
3. Identify the role of phosphorylation: After dimerization, specific tyrosine residues on the intracellular part of the RTKs are phosphorylated. This phosphorylation creates docking sites for other proteins that propagate the signal inside the cell.
4. Link the process to the options given: Both dimerization and phosphorylation are mentioned in option (a), aligning with the known activation mechanism of RTKs.
5. Eliminate other options: Options (b), (c), and (d) involve processes or molecules (IP3 binding, a phosphorylation cascade, GTP hydrolysis) that are not directly involved in the initial activation of RTKs.

Key Concepts

Receptor Tyrosine Kinases (RTKs)

Receptor tyrosine kinases are a class of cell surface receptors that, upon binding to their specific ligands, undergo dimerization. This process brings two receptor molecules together, which is crucial for their activation and subsequent signaling pathways. RTKs play a significant role in regulating various cellular processes, including growth, differentiation, and metabolism.

Dimerization

Dimerization refers to the process where two receptor molecules come together to form a dimer. In the context of RTKs, this is a critical step for their activation, as it allows the intracellular kinase domains to come into proximity, facilitating autophosphorylation. This phosphorylation event is essential for initiating downstream signaling cascades that influence cellular responses.

Phosphorylation

Phosphorylation is the addition of a phosphate group to a protein or other organic molecule, which can alter the molecule's function and activity. In RTKs, autophosphorylation occurs after dimerization, leading to the activation of the receptor and the recruitment of downstream signaling proteins. This modification is a key mechanism in cellular signaling, affecting processes such as cell division and survival.