Receptor-Mediated Transfer of Proteins from Blood to Bile
Bile proteins derive from several different sources. Firstly there is a small, mol. wt.-dependent, leakage of proteins across the tight junctions between liver cells. Secondly, proteins are solubilized from the bile-canalicular face of hepatocytes and from the luminal face of bile-duct lining cells. Thirdly there is discharge of the contents of lysosomes into bile. Finally there is selective transport of proteins across hepatocytes from blood to bile, the mechanism of which we have established by methods described in this article.
Firstly we consider how we identified which proteins are actively transported from blood to bile. In rats three proteins are thus transported: IgA, haemoglobin (in the form of hapto-globin: haemoglobin complexes) and an unidentified protein. Then we consider methods used to identify the receptors for these proteins; we have identified the receptor for IgA transport but not that for haemoglobin. Finally we describe how we investi-gated the mechanism by which the proteins move across the cell. This involves endocytosis into specialized vesicles which do not fuse with lysosomes but which follow a route across the cell very similar to that taken by proteins destined for lysosomal digestion; they are taken up from the sinusoidal face into small vesicles which move rapidly to the vicinity of the Golgi apparatus (G.a.) and then discharge into the bile canaliculus.
KeywordsTight Junction Perfuse Liver Bile Canaliculus Secretory Component Bromphenol Blue
Unable to display preview. Download preview PDF.
- 2.Orlans, E., Peppard, J., Fitzharris, B., Payne, A, Mullock, B.M., Hinton, R.H. & Hall, J. (1983) Ann. N.Y. Acad. Sci., in press.Google Scholar
- 3.Axelsen, N.H., Kroll, J. & Weeke, B. (1973) A Manual of Quantitative Immuno-electrophoresis, Universitetforlaget, Oslo.Google Scholar
- 5.Maizel, J. (1971) Meths. Virol. 5, 179–246.Google Scholar
- 6.Higa, Y., Oshiro, S., Kino, K., Tsunoo, H. & Nakiyima, H. (1981) J. Biol. Chem. 256, 12322–12328.Google Scholar
- 11.Dive, C. & Heremans, I.F. (1974) Eur. J. Clin. Invest, 4, 235–239.Google Scholar
- 12.Smith, R.L. (1973) The Excretory Function of Bile, Chapman & Hall, London, 394 pp.Google Scholar
- 13.Reid, E., ed, (1.979) Cell Populations [Vol. 8, this series], Horwood, Chichester, 240 pp.Google Scholar
- 14.Reid, E., Cook, G.M.W. & Morré, D.J. (1981) Cancer- Cell Organelles [Vol. 11, this series], Horwood, Chichester, 415 pp.Google Scholar
- 16.Wisher, M.H. & Evans, W.H. (1975) Biochem. J. 146, 375–388.Google Scholar
- 17.Graham, J.G. (1983) in Iodinated Density Gradient Media — A Practical Approach (Rickwood, D., ed.), IRL, Oxford, in press.Google Scholar
- 18.Mullock, B.M. & Hinton, R.H. (1983) Eur.J. Cell Biol. Suppl. 1, 31.Google Scholar
- 19.Birbeck, M.S.C., Cartright, C.P., Hall, J.G., Orlans, F. & Peppard, J. (1979) Immunology 37, 477–484.Google Scholar
- 26.Grant, D.A.W., Jones, P.A. & Heron-Taylor, J. (1981) Biochem. J. 198, 315–319.Google Scholar
- 27.Godfrey, P.P., Warner, M.J. & Coleman, R. (1981) Biochem. J. 136, 11–16.Google Scholar
- 28.Slot, J.W., Peppard, J. & Geuze, H.J. (1983) Abstracts, Br. Soc. Cell Biol. Mtg., Liverpool. Google Scholar