Cyclic AMP (cAMP), Ca²⁺, and IP₃ are examples of
- A
Membrane receptors — transmembrane proteins that detect external chemical signals
- B
First messengers — extracellular signaling molecules that bind to surface receptors
- Ccheck_circle
Second messengers — small intracellular molecules that propagate signals
- D
Adapter proteins — scaffolding molecules that organize relay components into pathways
Explanation
Second messengers amplify and spread the signal received at the membrane, triggering many downstream responses.