Peripheral membrane protein
（重定向自Peripheral membrane proteins）
![Schematic representation of the different types of interaction between monotopic membrane proteins and the cell membrane:
1. interaction by an amphipathic α-helix parallel to the membrane plane (in-plane membrane helix)
2. interaction by a hydrophobic loop
3. interaction by a covalently bound membrane lipid (lipidation)
4. electrostatic or ionic interactions with membrane lipids (e.g. through a calcium ion)](/Images/godic/202502/02/Monotopic_membrane_protein.svg0520.png")
![PH domain of phospholipase C delta 1. Middle plane of the lipid bilayer – black dots. Boundary of the hydrocarbon core region – blue dots (intracellular side). Layer of lipid phosphates – yellow dots.](/Images/godic/202502/02/1mai0520.png")
![Bee venom phospholipase A2 (1poc). Middle plane of the lipid bilayer – black dots. Boundary of the hydrocarbon core region – red dots (extracellular side). Layer of lipid phosphates – yellow dots.](/Images/godic/202502/02/1poc0520.png")
![P40phox PX domain of NADPH oxidase Middle plane of the lipid bilayer – black dots. Boundary of the hydrocarbon core region – blue dots (intracellular side). Layer of lipid phosphates – yellow dots.](/Images/godic/202502/02/1h6h0520.png")
Peripheral Membrane Proteins are membrane proteins that adhere only temporarily to the biological membrane with which they are associated. These proteins attach to integral membrane proteins, or penetrate the peripheral regions of the lipid bilayer. The regulatory protein subunits of many ion channels and transmembrane receptors, for example, may be defined as peripheral membrane proteins. In contrast to integral membrane proteins, peripheral membrane proteins tend to collect in the water-soluble component, or fraction, of all the proteins extracted during a protein purification procedure. Proteins with GPI anchors are an exception to this rule and can have purification properties similar to those of integral membrane proteins.