The 240-kDa subunit of human erythrocyte spectrin binds calmodulin at micromolar calcium concentrations.
The binding of the isolated alpha-subunit of human erythrocyte spectrin to calmodulin is demonstrated by partitioning in aqueous two-phase systems. The affinity of the alpha-subunit for calmodulin is slightly higher than that of the spectrin dimer, whereas the beta-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 microM free calcium is required to induce maximum binding of calmodulin to spectrin dimer.
Berglund
A
A
Backman
L
L
Shanbhag
V P
VP
D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000378:metabolism*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002746:Chlorpromazine / Q000494:pharmacology; D006801:Humans; D046911:Macromolecular Substances; D009994:Osmolar Concentration; D011485:Protein Binding / Q000187:drug effects; D011487:Protein Conformation; D013049:Spectrin / Q000378:metabolism*
D002147:Calmodulin; D046911:Macromolecular Substances; D013049:Spectrin; D002118:Calcium; D002746:Chlorpromazine