Fluidity in mitochondrial membranes: thermotropic lateral translational motion of intramembrane particles.
The fracture faces of frozen rat liver mitochondria reveal that intramembrane particles can be induced to under go long-range lateral translational motion and aggregation, which parallel the appearance of large, particle-free smooth patches in the hydrophobic interior of the two mitochondrial membranes. These lateral separations were observed under conditions that induce thermotropic lipid-lipid phase separations. Low temperature-induced lateral separation occurred between the intramembrane particles (integral proteins) and smooth patches (bilayer lipid) at temperatures between about 10 and -12 degrees in the outer membrane and between about -4 and -12 degrees in the inner, energy transducing membrane.
D000818:Animals; D005614:Freeze Fracturing; D008297:Male; D008566:Membranes / Q000502:physiology / Q000648:ultrastructure; D008930:Mitochondria, Liver / Q000648:ultrastructure*; D009038:Motion; D010085:Oxidative Phosphorylation; D051381:Rats; D013696:Temperature