Association of annexin A7 and sorcin with distinct red blood cell plasma membrane fractions. Lysed human red blood cells were added to a self forming iodixanol density gradient. The density of the gradient increases from left (1.06 g/ml) to right (1.20 g/ml). Fractions were analysed by immunoblotting using mAb 203–217 and the sorcin polyclonal antibody.