spectrinbased

The spectrin-based cytoskeleton, or spectrin-based membrane skeleton, is a flexible protein network beneath the plasma membrane. It is best characterized in red blood cells but is present in many cell types, where it supports membrane integrity and helps preserve cell shape during mechanical stress.

Core components include spectrin dimers that assemble into tetramers composed of alpha- and beta-spectrin chains. These tetramers associate with short actin filaments and accessory proteins such as adducin and tropomyosin at junctional complexes. Ankyrin links the cytoskeletal lattice to the membrane by binding to band 3 and other integral membrane proteins, anchoring the network to the bilayer.

Functionally, the spectrin-based network provides elasticity and resilience, limits membrane fluctuations, and helps organize membrane domains and signaling proteins. It supports rapid shape changes and mechanical deformation, enabling red blood cells to traverse narrow capillaries without rupturing.

Assembly and regulation involve dynamic remodeling of the spectrin–actin network. Tetramers connect along actin filaments; adducin caps and promotes spectrin assembly at actin ends, promoting lattice formation. Phosphorylation and interactions with ankyrin modulate connections to membrane proteins, allowing remodeling during development and in response to stress.

Clinical relevance includes mutations in spectrin, ankyrin, and associated proteins that cause hereditary spherocytosis and elliptocytosis, leading to hemolytic anemia. The spectrin-based cytoskeleton is a focus in studies of red cell biology, membrane integrity, and broader cytoskeletal organization in health and disease.