A neuron synthesizes and secretes substance D, which binds to a receptor on the neuron cell membrane, triggering an influx of calcium. Substance D therefore is a ligand for a ____.
A) a receptor tyrosine kinase
B) a G-protein-coupled receptor
C) a hormone receptor
D) a ligand-gated ion channel
E) guanylyl cyclase

Question

Quizplus · Accepted Answer

Substance D acts as a ligand for a ligand-gated ion channel, as indicated by its role in binding to a receptor that directly triggers an influx of calcium ions into the neuron. This is characteristic of ligand-gated ion channels, which open in response to the binding of a ligand, allowing specific ions to flow across the membrane.

A Neuron Synthesizes and Secretes Substance D, Which Binds to a Receptor