An irreversible antagonist is a type of antagonist that binds permanently to a receptor

Receptor (biochemistry)

In biochemistry, a receptor is a molecule found on the surface of a cell, which receives specific chemical signals from neighbouring cells or the wider environment within an organism...

, either by forming a covalent bond

Covalent bond

A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding....

 to the active site, or alternatively just by binding so tightly that the rate of dissociation is effectively zero at relevant time scales. This permanently deactivates the receptor and is usually followed by rapid internalisation

Receptor-mediated endocytosis

Receptor-mediated endocytosis , also called clathrin-dependent endocytosis, is a process by which cells internalize molecules by the inward budding of plasma membrane vesicles containing proteins with receptor sites specific to the molecules being internalized.-Process:After the binding of a...

 and recycling of the non-functional receptor protein.

See also

• Irreversible agonist
• Irreversible enzyme inhibitor