Intramembrane proteases (IMPs), also known as intramembrane-cleaving proteases (I-CLiPs), are enzymes that have the property of cleaving transmembrane domains of integral membrane proteins. All known intramembrane proteases are themselves integral membrane proteins with multiple transmembrane domains, and they have their active sites buried within the lipid bilayer of cellular membranes.
Intramembrane proteases are not evolutionarily related to classical soluble proteases, having evolved their catalytic sites by convergent evolution.
Although only recently discovered, intramembrane proteases are the focus of intense interest because of their major biological functions and their implication in many human diseases.
Classification
Four major classes of intramembrane proteases have been discovered: