we found that monensin did not significantly affect either the subcellular fractionation , or the distribution of organelle marker enzymes along the gradient , and that procollagen moved from a region of high buoyant density ( primarily endoplasmic reticulum ) , through a mid-density region ( primarily golgi elements ) , to a region of low buoyant density before exiting from the cell .
C0014239
endoplasmic
C0007634
cell