Involvement of a cytoplasmic protein in calcium-dependent potassium efflux in red blood cells.

The potassium permeability of the human red blood cell increases with the free intracellular calcium concentration. The efflux of potassium can be inhibited by iodoacetic acid. This inhibitory effect correlates directly with the carboxymethylation of a protein band found in both the hemolysate and membrane fractions. The present study provides two additional lines of evidence that this protein is involved directly with the calcium-dependent changes in potassium permeability: its association with the membrane is calcium dependent; and calcium-dependent potassium efflux from resealed ghost is inhibited by the incorporation of antibodies raised against this cytoplasmic protein.