The 240-kDa subunit of human erythrocyte spectrin binds calmodulin at micromolar calcium concentrations

AbstractThe binding of the isolated α-subunit of human erythrocyte spectrin to calmodulin is demonstrated by partitioning in aqueous two-phase systems. The affinity of the α-subunit for calmodulin is slightly higher than that of the spectrin dimer, whereas the β-subunit interacts only very weakly. The binding is in all cases calcium-dependent and is abolished on addition of chlorpromazine. At an ionic strength close to physiological conditions, about 1 μM free calcium is required to induce maximum binding of calmodulin to spectrin dimer.Calmodulin(Human)SpectrinErythrocyte cytoskeletonAqueous two-phase partitionin