Unconjugated bilirubin exhibits spontaneous diffusion through model lipid bilayers and native hepatocyte membranes.

@article{Zucker1999UnconjugatedBE,
  title={Unconjugated bilirubin exhibits spontaneous diffusion through model lipid bilayers and native hepatocyte membranes.},
  author={Stephen D. Zucker and Wolfram Goessling and Alison G Hoppin},
  journal={The Journal of biological chemistry},
  year={1999},
  volume={274 16},
  pages={10852-62}
}
The liver is responsible for the clearance and metabolism of unconjugated bilirubin, the hydrophobic end-product of heme catabolism. Although several putative bilirubin transporters have been described, it has been alternatively proposed that bilirubin enters the hepatocyte by passive diffusion through the plasma membrane. In order to elucidate the mechanism of bilirubin uptake, we measured the rate of bilirubin transmembrane diffusion (flip-flop) using stopped-flow fluorescence techniques… CONTINUE READING