Elastic Properties of Layered Membranes and Their Role in Transformations of Cellular Shapes
Biological membranes are in general layered structures. Phospholipid bilayers as their basic structural unit are composed of two opposing phospholipid monolayers. Many biological membranes have as an additional layer a bilayer linked two-dimensional intracellular network of skeletal proteins. An extracellular matrix can also be considered as a separate layer parallel to other membrane layers. In the work presented here it is taken that membrane layers are in contact but unconnected in the sense that they are free to slide one by the other. Each layer can thus establish its lateral elastic equilibrium in an independent manner. Such physical picture of biological membranes has structural grounds. The two monolayers of a phospholipid bilayer are in contact because of the hydrophobic effect and are unconnected as there are no direct bonds between their molecules. Membrane cytoskeletons are in general in contact with the phospholipid part of the membrane by being attached to it by bonds to the integral membrane proteins. When these proteins can move laterally in the phospholipid milieu sufficiently freely, the cytoskeleton can also be considered as an unconnected membrane layer.
KeywordsElastic Energy Membrane Layer Phospholipid Vesicle Neutral Surface Spontaneous Curvature
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