A quantitative study of the subcellular localization of 67Ga

This paper describes a quantitative procedure for the isolation of 67 Ga-binding granules (GBG) from normal rat liver and Morris 5123C hepatoma homogenates by a combination of rate and isopyknic density gradient zonal centrifugation. Another class of GBG has been found that is much smaller than the lysosomal GBG we have previously described. These smaller particles, or microvesicles, bind the largest portion of the 67Ga found in the hepatoma whereas, in the liver, the GBG lysosomes are the major binding component. Previously, we had shown that considerably more 67Ga is taken up in hepatoma than in liver (as percentage of administered dose per g of tissue). The preferential association of 67Ga with these microvesicles in the 5123C hepatoma may be indicative of a basic difference between normal and malignant tissue.