Identification and purification of a 36 kDa bile acid binder in human hepatic cytosol.
We recently purified two closely related 33 kDa proteins from rat hepatic cytosol, designated bile acid binder I and II, which selectively bind bile acids with comparable affinity as glutathione S-transferase B. This work has now been extended to human liver in which we have identified a similar cytosolic binding activity in the 30-40 kDa fraction from gel filtration. Subsequent chromatofocusing and hydroxyapatite chromatography resulted in the isolation of a homogeneous monomeric protein of 36 kDa. The binding affinity of this protein for lithocholate using the displacement of 1-anilino-8-naphthalenesulfonate (ANS) was 0.1 microM, whereas human hepatic glutathione S-transferases purified from glutathione affinity chromatography demonstrated no competitive displacement of ANS.
D000596:Amino Acids / Q000032:analysis; D002352:Carrier Proteins / Q000302:isolation & purification*; D002850:Chromatography, Gel; D003600:Cytosol / Q000032:analysis; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D006913:Hydroxysteroid Dehydrogenases; D007525:Isoelectric Focusing; D008095:Lithocholic Acid / Q000378:metabolism; D008099:Liver / Q000032:analysis*; D008562:Membrane Glycoproteins; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific)
D000596:Amino Acids; D002352:Carrier Proteins; D005982:Glutathione Transferase; D006913:Hydroxysteroid Dehydrogenases; D008095:Lithocholic Acid; D008562:Membrane Glycoproteins; C037643:bile acid binding proteins; C435496:AKR1C2 protein, human; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific)