Which of the following is activated when the binding of single molecules causes it to form a dimer?

• A. Ion-channel receptors
• B. Protein phosphatase receptors
• C. G-protein-coupled receptors
• D. Adenylyl cyclase receptors
• E. Receptor tyrosine kinases

Answer: (E)

Verified step by step guidance

1. Understand the concept of receptor tyrosine kinases (RTKs): These are a class of receptors that are activated by the binding of signaling molecules, leading to the formation of a dimer.
2. Recognize the process of dimerization: When a signaling molecule binds to the extracellular domain of an RTK, it causes two receptor molecules to come together and form a dimer.
3. Identify the role of dimerization in activation: The dimerization of RTKs leads to the activation of their intrinsic kinase activity, which is crucial for the subsequent phosphorylation of tyrosine residues on the receptor itself and on downstream signaling proteins.
4. Differentiate RTKs from other receptor types: Ion-channel receptors, G-protein-coupled receptors, and adenylyl cyclase receptors do not typically undergo dimerization as a mechanism of activation.
5. Conclude that receptor tyrosine kinases are the correct answer: Based on the understanding of their activation mechanism through dimerization, RTKs are the receptors that fit the description in the problem.