Receptor (biochemistry)

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== Receptor (biochemistry) ==

A receptor in biochemistry is a protein molecule that receives and responds to a neurotransmitter, hormone, or other substance. Receptors are typically found on the surface of a cell membrane, but they can also be located within the cell. When a substance binds to a receptor, it causes a change in the receptor's structure, which can trigger a series of cellular responses.

Types of Receptors

Receptors can be classified into several types based on their location and the type of ligand they bind to:

• Cell surface receptors: These receptors are embedded in the plasma membrane of cells. They include:

* G protein-coupled receptors (GPCRs)
* Ion channel receptors
* Enzyme-linked receptors

• Intracellular receptors: These receptors are located inside the cell, typically in the cytoplasm or nucleus. They include:

* Nuclear receptors

Mechanism of Action

When a ligand binds to a receptor, it induces a conformational change in the receptor. This change can activate or inhibit the receptor's associated signal transduction pathways. For example:

• In GPCRs, the binding of a ligand activates a G protein, which then activates or inhibits other proteins in the cell.
• In ion channel receptors, the binding of a ligand opens or closes the channel, allowing ions to flow into or out of the cell.
• In enzyme-linked receptors, the binding of a ligand activates an associated enzyme, which then triggers a cascade of cellular events.

Functions

Receptors play a crucial role in various physiological processes, including:

• Neurotransmission
• Hormone signaling
• Immune response
• Cell growth and differentiation

Examples of Receptors

Some well-known examples of receptors include:

• Adrenergic receptors, which respond to adrenaline and noradrenaline
• Dopamine receptors, which respond to dopamine
• Insulin receptors, which respond to insulin
• Estrogen receptors, which respond to estrogen

Clinical Significance

Receptors are important targets for many pharmaceutical drugs. For example:

• Beta-blockers target adrenergic receptors to treat hypertension and cardiovascular disease.
• Antipsychotics target dopamine receptors to treat schizophrenia and other mental disorders.
• Insulin therapy targets insulin receptors to manage diabetes mellitus.

See Also

• Ligand (biochemistry)
• Signal transduction
• Cell signaling
• Pharmacology