Its sure to be a G protein-linked receptor. Its a classic tyrosine-kinase receptor response. Perhaps its a ligand-gated ion channel e. Most likely, its a phosphorylated tyrosine dimer responding. Ligand is any small molecule that can bind to a larger molecule.
Ligand is the target cell of a signal molecule.
Ligand is a molecule that can occupy a receptor site while NOT activating it. It is reduced and then carries electrons to the Calvin cycle. It assists photosystem II in the splitting of water. It assists chlorophyll in capturing light. It acts as the primary electron acceptor for the photosystems.