Notes:
Effect of FITC labelling on the EM structure. The left-hand image (yellow) corresponds to our published structure of rabbit Ca-ATPase in presence of decavanadate and dansyl-thapsigargin. The right-hand image (cyan) was created from the same preparation after FITC labelling the Ca-ATPase. A strong, spherical density is by FITC and almost certainly corresponds to the intramolecular decavanadate binding site. The lower panels are sections parallel to the membrane; the arrow points to the intramolecular decavanadate density, which is missing after FITC labelling. The circles are drawn around intermolecular decavanadate; these are weaker densities because they are centered a few sections below the one shown. These intermolecular decanadate molecules are unaffected by FITC labelling.