A reliable method for assessing topographical arrangement of proteins in the chromaffin granule membrane

An efficient and reliable method for preparing chromaffin granules and membranes for topographical analysis has been designed to meet the following criteria. Only labeling of truly intact organelles is analyzed for cytoplasmic surface probes. No resealing of open membranes occurs under specified reaction conditions. Saturation of available sites must be demonstrated. Problems in meeting these conditions are discussed, in particular the interference of granule lysate with labeling reactions.