ROS Plasma Membrane

Bovine photoreceptor cell (ROS). EF and ES faces of the plasma membrane.

The formation of IMP free patches is probably a preparation artifact. The sample was fixed by rapid freezing, i.e. immersion in liquid propane, from room temperature (RT). The temperature difference between RT and physiological temperatures may lead to a phase separation of lipids and IMPs in the membranes.

In the central part the exoplasmic leaflet of the plasma membrane is conserved. The molecular binding forces of the IMPs were strong enough to preserve the whole plasma membrane. In the IMP free areas and the remaining IMP patches the fracture plane goes through the hydrophobic core of the membrane.

bar: 250nm, Freeze Fracture