Fig. 5. Distribution of rat intestinal subcellular organelles separated on an iodixanol gradient identifying VAMP7 in both ER and endosomes. Post nuclear supernatant protein (2 mg) was separated on a 10-40% iodixanol gradient. The gradient was centrifuged and resolved as described in the Materials and Methods and the fractions obtained indicated. The proteins in each fraction (50 µl) were separated by 12% SDS-PAGE, transblotted to a membrane and the location of calreticulin, VAMP7, Rab11, Sec22b and Syntaxin8 identified by immunoblotting with their specific antibodies.