Carcinoembryonic antigen-related cell adhesion molecule 1 is the 85-kilodalton pronase-resistant biliary glycoprotein in the cholesterol crystallization promoting low density protein-lipid complex

Authors

  • Milan Jirsa,

    Corresponding author
    1. First Department of Internal Medicine, First Faculty of Medicine, Charles University, Prague, Czech Republic
    2. Department of Gastrointestinal and Liver Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
    • Laboratory of Experimental Hepatology, Room F0-116, Department of Liver and Gastrointestinal Diseases, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. fax: (31) 20 566 9190
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  • Lucie Muchová,

    1. First Department of Internal Medicine, First Faculty of Medicine, Charles University, Prague, Czech Republic
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  • Lubica Dráberová,

    1. Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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  • Petr Dráber,

    1. Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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  • František Šmíd,

    1. First Department of Internal Medicine, First Faculty of Medicine, Charles University, Prague, Czech Republic
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  • Masahide Kuroki,

    1. First Department of Biochemistry, Fukuoka University School of Medicine, Fukuoka, Japan
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  • Zdenčk Mareček,

    1. First Department of Internal Medicine, First Faculty of Medicine, Charles University, Prague, Czech Republic
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  • Albert K. Groen

    1. Department of Gastrointestinal and Liver Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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Abstract

A pronase resistant 85-kd glycoprotein in the Concanavalin A–binding fraction (CABF) of biliary glycoproteins has been reported to act as a promotor of cholesterol crystallization. De Bruijn et al. (Gastroenterology 1996;110:1936-1944) found this protein in a low-density protein-lipid complex (LDP) with potent cholesterol crystallization promoting activity. This study identifies and characterizes this protein. An LDP was prepared from CABF by discontinuous gradient ultracentrifugation. Proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), blotting and immunochemical staining with anti-carcinoembryonic antigen, CEA-related adhesion molecule 1 (CEACAM1) cross-reacting antibodies. Biliary concentrations of CEA cross-reacting proteins were determined in patients with and without gallstones. Two isoforms of CEACAM1 (85- and 115-kd bands), CEA and 2 CEA cross-reacting protein bands of 40 and 50 kd were found in human bile. All bands were also present in CABF, but only a subfraction of the 85-kd band found in the LDP was resistant to digestion with pronase. CEACAM1-85 exhibited potent cholesterol crystallization promoting activity in vitro and accounted for most of the activity in CABF. Total CEA cross-reacting protein concentrations were the same in gallbladder biles from patients with cholesterol and pigment gallstones but only half of those in biles from nongallstone subjects. In conclusion, we have identified the protein component of the cholesterol crystallization promoting LDP to be CEACAM1-85.

Ancillary

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