Endogenous extracellular molecules X and Y both bind to a receptor on the target cell. Binding of molecule X to the receptor results in changes in the cell's behavior. Binding of molecule Y does not result in changes in the cell's behavior. Which molecule can be called the ligand?
A) only molecule X
B) only molecule Y
C) neither molecule X nor Y
D) both molecules X and Y

Question

Quizplus · Accepted Answer

Both molecules X and Y can be called ligands because they both bind to a receptor on the target cell, regardless of whether they elicit a response.

Endogenous Extracellular Molecules X and Y Both Bind to a Receptor