Inhibition of anion permeability of sarcoplasmic reticulum vesicles by stilbene derivatives and the identification of an inhibitor-binding protein.

The permeability of sarcoplasmic reticulum vesicles to sulfate ions was inhibited by diisothiocyano-1,2-diphenylethane-2,2'-disulfonic acid (H2DIDS), which is a potent inhibitor of anion permeability in red blood cell membrane. The amount of H2DIDS bound to the vesicles was determined by using [3H]-H2DIDS. Apparent half inhibition of sulfate permeation was observed on the binding of 2.5 mumol/g protein. SDS-polyacrylamide gel electrophoresis on the vesicles treated with [3H]H2DIDS showed that about 10% of the total bound H2DIDS corresponds to a 100 000-dalton protein, but the remaining 90% to non-protein components. The content of the H2DIDS-binding protein was about 0.5 mumol/g protein. These results suggest that the H2DIDS-binding protein is different from the calcium pump protein and is possibly an anion transport system similar to band 3 in red blood cell membrane.