Answer:
Signal transduction
Step-by-step explanation:
Ligand forms complexes with substance and a ligand protein binds to a target site on protein and produces a signals on binding to it.
Signal transduction is the process by which signals both physical and chemical are transmitted through a cell via a series of molecular events especially protein phosphorylation catalyzed by protein kinases that results in a cellular response.
Receptors are proteins that detect stimuli. The changes that comes from ligand binding a receptor give rise to a biochemical cascade.