What Is a Receptor on a Cell and What Does It Do?

Cells, such as the ones in the human body, need a way to interact and communicate with substances such as hormones, drugs, or even sunlight. That's where cellular receptors come in.

A receptor is a protein molecule in a cell or on the surface of a cell to which a substance (such as a hormone, a drug, or an antigen) can bind, causing a change in the activity of that particular cell.​

Here's one way to think of this: a receptor is like a lock, while the substance binding to it is the key to that lock. Only substances keyed to fit the receptor "lock" can bind to a particular receptor.

Substances binding to receptors on cells can tell the cell to produce a particular substance (such as a hormone that makes you feel full after a big meal), to divide faster (maybe causing you to add muscle cells following exercise) or even to die (chemotherapy drugs binding to cancer cell receptors can signal those cancer cells to self-destruct).

Cells' receptors are very specialized and there are in fact hundreds of different types of receptors. Most respond to chemical substances such as hormones, drugs or allergens, while some even respond to pressure or light (your body produces vitamin D, the "sunshine hormone" when sunlight hits your skin).

In some cases, if a cell doesn't have the correct receptor for a particular substance, then that substance won't affect the cell.

For example, leptin is the hormone that causes you to feel full and satiated following a big meal. Cells that don't have receptors for leptin won't respond to that hormone, but cells that do have receptors for leptin will respond to it, inhibiting the release of other hormones that make you want to eat more.

Receptors can play both good and bad roles in the human body.

In celiac disease, for example, receptors on specific immune system cells serve as the locks and fragments of the gluten protein serve as the keys, triggering celiac's characteristic intestinal damage known as villous atrophy.

Certain cellular receptors also appear to play a role in causing damage in other autoimmune diseases. In an autoimmune disease, your immune system mistakenly turns on and damages some of your body's own cells. Celiac disease is an autoimmune disease.

But in high blood pressure, drugs can fit as keys into the cellular receptors that otherwise would fit a hormone that raises blood pressure. These drugs, known as angiotensin-blockers because they block the blood pressure-raising hormone angiotensin, can help control your blood pressure by preventing angiotensin from signaling your cells to raise blood pressure.

(Edited by Jane Anderson)