What's new in the hepatocellular uptake mechanism of bilirubin and fatty acids?
Although hepatocellular uptake of bilirubin and fatty acids represents a major function of the liver, little was known about the molecular mechanism of their translocation across the plasma membrane. This review provides evidence that these classes of albumin-bound organic anions enter hepatocytes via specific membrane associated carrier systems. After dissociation of the albumin-ligand complexes at the cell surface, bilirubin and related cholephilic organic anions bind to a 55 kDa membrane glycoprotein, while fatty acids bind to a 40 kDa membrane protein. Both proteins function as carrier of their respective ligand across the plasma membrane. Although the driving forces for the influx of bilirubin are still unknown, it could be demonstrated that the translocation of fatty acids across the plasma membrane is driven by an active, potential-sensitive, sodium-dependent transport system.
Stremmel
W
W
Department of Internal Medicine, University of Düsseldorf, FRG.
D001663:Bilirubin / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D006801:Humans; D008099:Liver / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D017457:Receptors, Albumin; D011956:Receptors, Cell Surface / Q000502:physiology
D005227:Fatty Acids; D017457:Receptors, Albumin; D011956:Receptors, Cell Surface; D001663:Bilirubin