Effect of detergent treatment on the cross-linking of purified chromaffin granule membranes with F-actin

Chromaffin granule-microfilament interaction has previously been proposed to play a potential role in the regulation of dopamine uptake into the granules as well as catecholamine secretion in the adrenal medullary cell. However, the microfilament-binding site on the granule surface has not yet been identified. To establish the conditions for solubilization of the binding site, the effects of different-type detergents on the cross-linking of chromaffin granule membranes with F-actin were examined. The cross-linking activity was abolished by treatment of the granule membranes with deoxycholate (DOC), but not Triton X-100 (TX100) and CHAPS. The addition of DOG-extract decreased the viscosity of F-actin solution, suggesting that solubilized proteins bind to F-actin, but not cause the cross-linking of actin filaments. These results indicate that the actin-binding site can be solubilized from chromaffin granule membranes by DOC treatment.