Nitric Oxide signals by binding to which of the following molecules?

• A. GTPases
• B. Nuclear Receptors
• C. Adenyl cyclase
• D. Guanyl cyclase

Answer: (D)

Verified step by step guidance

1. Understand the role of Nitric Oxide (NO) in cell signaling. NO is a gaseous signaling molecule that can diffuse across cell membranes and is involved in various physiological processes.
2. Recognize that NO primarily functions by activating specific enzymes within the cell. It does this by binding to these enzymes, which then trigger a signaling cascade.
3. Identify the enzyme that NO binds to in order to exert its effects. In this context, NO binds to guanylyl cyclase, an enzyme that catalyzes the conversion of GTP to cyclic GMP (cGMP).
4. Differentiate guanylyl cyclase from other molecules listed in the options. GTPases are involved in hydrolyzing GTP, nuclear receptors are involved in gene expression regulation, and adenyl cyclase converts ATP to cyclic AMP (cAMP).
5. Conclude that the correct molecule that NO binds to is guanylyl cyclase, as it directly interacts with NO to produce cGMP, a secondary messenger involved in vasodilation and other cellular responses.