Synthesis of two forms of apolipoprotein B by cultured rat hepatocytes

Cultured rat hepatocytes were used to demonstrate that the liver can synthesize two forms of apolipoprotein B. Separation of apolipoprotein B by disc gel electrophoresis indicated that hepatocyte low density lipoprotein contains predominantly apolipoprotein B with an apparent molecular weight of 345,000 ± 5,055. In contrast, the major apolipoprotein B component of hepatocyte very low density lipoprotein is a variant form with a molecular weight of 242,000 ± 2,720. Hepatocyte high density lipoprotein, unlike plasma HDL, also contains apolipoprotein B with an apparent molecular weight of 244,000 ± 2,742. Incorporation of ³H] leucine into hepatocyte apolipoprotein B components suggested de novo synthesis.