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Gastroenterology. 1999 Mar;116(3):643-9.

Formiminotransferase cyclodeaminase is an organ-specific autoantigen recognized by sera of patients with autoimmune hepatitis.

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Service de Gastroentérologie et Nutrition, Hôpital Sainte-Justine, Montréal, Québec, Canada.



Anti-liver cytosol type 1 autoantibodies have been reported in association with anti-liver-kidney microsome type 1 autoantibodies in 30% of patients with autoimmune hepatitis type II. In 10% of cases, anti-liver cytosol type 1 antibodies are the only liver-related circulating autoantibodies. The liver cytosol antigen is a liver-specific 62-kilodalton protein present in the cell as an oligomer of approximately 240 kilodaltons. The aim of this study was to identify the antigen recognized by anti-liver cytosol antibody.


To identify the liver cytosol antigen, an anti-liver cytosol type 1-positive serum was used for the screening of a complementary DNA library from HepG2 cells. Double immunodiffusion method was used to show the identity between the cytosolic and the cloned protein.


The sequence of two isolated clones showed 85.2% homology with the formiminotransferase cyclodeaminase (FTCD) enzyme from pig liver. Antibodies purified by affinity with the recombinant protein and sera from mice immunized with FTCD recognized a 62-kilodalton human cytosolic protein when tested by immunoblot. The identity of precipitation lines was found between the cytosolic antigen and FTCD.


This enzyme is a liver-specific antigen recognized by the sera of patients with autoimmune hepatitis.

[Indexed for MEDLINE]

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