EFFECT OF DETERGENT TREATMENT ON THE CROSS-LINKING OF PURIFIED CHROMAFFIN GRANULE MEMBRANES WITH F-ACTIN

Chromaffin granule-microfilament interaction has previously been propo sed to play a potential role in the regulation of dopamine uptake into the granules as well as catecholamine secretion in the adrenal medull ary cell. However, the microfilament-binding site on the granule surfa ce has not yet been identified. To establish the conditions for solubi lization of the binding site, the effects of different-type detergents on the cross-linking of chromaffin granule membranes with F-actin wer e examined. The cross-linking activity was abolished by treatment of t he granule membranes with deoxycholate (DOC), but not Triton X-100 (TX 100) and CHAPS. The addition of DOG-extract decreased the viscosity of F-actin solution, suggesting that solubilized proteins bind to F-acti n, but not cause the cross-linking of actin filaments. These results i ndicate that the actin-binding site can be solubilized from chromaffin granule membranes by DOC treatment.