Which of the following is a structural protein providing support to the RBC membrane?
Erythrocyte membrane mechanical resilience originates from spectrin ankyrin network linkage. Ankyrin-1 large adaptor of approximately two hundred six kilodaltons comprises three domains: N-terminal membrane binding domain of twenty four ankyrin repeats each thirty three residues forming elongated solenoid that binds high affinity site on Band 3 cytoplasmic domain residues one seventy five to one eighty five and other integral proteins sodium-potassium ATPase, sodium channel Nav1.5, cell adhesion molecule L1; central spectrin binding domain of about one hundred residues binding beta spectrin repeat fourteen to fifteen; C-terminal regulatory domain including death domain modulating affinity. Ankyrin bridges Band 3 to beta spectrin tetramer about two hundred nanometers comprising antiparallel alpha beta heterodimers assembling head to head. Protein 4.1R complex links glycophorin C to junctional actin spectrin nodes. Quantitative deficiency reduces spectrin incorporation about fifty percent leading to hereditary spherocytosis spherocytic rigid cells hemolysis splenomegaly. Thus ankyrin provides vertical coupling essential for biconcave disc stability during circulation through narrow capillaries and prevents vesiculation under shear stress.
Ref: Bennett and Healy, Membrane Protein Complexes and Ankyrin Function, Annu Rev Cell Dev Biol.