Integral monotopic protein
![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/202501/20/Monotopic_membrane_protein.svg3942.png")
Integral monotopic proteins, are permanently attached to the membrane from one side.
Three-dimensional structures of the following integral monotopic proteins have been determined:
There are also structures of integral monotopic domains of transmembrane proteins: