Receptor

A receptor is a protein, usually on a cell's surface or in its interior, that binds a specific signaling molecule and converts that binding into a cellular response.

Receptors give chemical signals their meaning: the same hormone can excite one tissue and calm another depending on which receptor each expresses. Major families include ion channels, which open a pore when their ligand binds; G protein-coupled receptors, the largest family, which relay signals through intracellular G proteins and account for a large share of drug targets; enzyme-linked receptors such as those for insulin; and nuclear receptors, which bind DNA and regulate genes. Receptor numbers are not fixed; cells add or remove them in response to sustained signaling, producing tolerance or sensitization.

The cannabinoid receptors CB1 and CB2 are G protein-coupled receptors, and TRPV1 is an ion channel. CBD engages a number of receptors and channels directly or indirectly, most with modest affinity, and which of those interactions accounts for any given effect in a living body remains an open research question.