EVIDENCE FOR A HEPATOCYTE MEMBRANE FATTY-ACID TRANSPORT PROTEIN USINGRAT-LIVER MESSENGER-RNA EXPRESSION IN XENOPUS-LAEVIS OOCYTES

The aim of the present study was to directly demonstrate that hepatoce llular uptake of long-chain fatty acids represents a non-diffusional u ptake mechanism. Xenopus laevis oocytes were used for expression of ra t liver mRNA to identify the liver fatty acid uptake system. Injection of total rat liver poly(A)(+) RNA into oocytes resulted in a dose-dep endent increase in fatty acid uptake. The most active mRNA was found i n the 1.1-2.1 kb subfraction. In contrast, expression of the liver cyt osolic fatty acid binding protein (L-FABP) or the previously suggested candidate carrier protein, mitochondrial aspartate aminotransferase ( mGOT), did not induce fatty acid uptake. It is concluded that in rat l iver, fatty acid transport represents a protein-mediated transport sys tem.