Spectrin
Spectrin is a filamentous protein that is associated with the cytosolic side of the plasma membrane in red blood cells, forming a network that supports the membrane. This is particularly important in red blood cells so that they maintain their concave structure and so can continue to carry oxygen around the blood stream. Spectrin helps red blood cell to withstand high presure which exerted on its membrance when travelling in narrow capilaries[1]. Spectrin is also present in muscle fibres and is found as a tetramer of two alpha and two beta subunits in actin filaments[2].
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