Role of membrane-associated cytoskeleton in maintenance of membrane structure.
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Date
1985-08
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Abstract
Various structural components of biological membranes are asymmetrically
localized in the two surfaces of the membrane bilayer. This asymmetry is absolute for
membrane (glyco) proteins, but only a partial asymmetry has been observed for membrane
phospholipids. In the red cell membrane, choline-phospholipids are localized mainly in the
outer monolayer whereas aminophospholipids are distributed almost exclusively in the inner
monolayer. Several evidences are now available to suggest that this distribution of membrane
phospholipids in red cells is directly or indirectly maintained by the membrane-associated
cytoskeleton (membrane skeleton). This belief is well supported by the previous as well as
recent studies carried out in the authors laboratory. Previously, it has been shown that lipidlipid
interactions play no major role in maintaining the transmembrane phospholipid
asymmetry in erythrocytes, and that the asymmetry is lost upon covalent crosslinking of the
major membrane skeletal protein, spectrin. The recent data presented here further shows that
degradation or denaturation of spectrin indices rapid transbilayer movement of membrane
phospholipids in the cells which, in turn, leads to more random phospholipid distributions
across the membrane. These studies taken together strongly suggest that the skeletonmembrane
associations are the major determinants of the transmembrane phospholipid
asymmetry in erythrocytes, and that the dissociation of the skeleton from the membrane
bilayer probably results in generation of new reorientation sites for phospholipids in the
membrane.
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Keywords
Cytoskeleton, membrane bilayer, phospholipid asymmetry, phospholipases, erythrocytes
Citation
C M Gupta, Kumar A, Joshi P. Role of membrane-associated cytoskeleton in maintenance of membrane structure. Journal of Biosciences. 1985 Aug; 8(1&2): 355-362.