Molecular Cloning and Sequence Analysis of a Human 372-kDa Protein Localized in the Golgi Complex

Autoantibodies from a patient with chronic rheumatoid arthritis recognized an antigen localized in the Golgi complex of various cells from different tissues and species. The autoantibodies were used as a probe for screening human QGP-1 cDNA library, resulting in identification of a 10.3kb cDNA. The cDNA insert contained an open reading frame which encodes a 3225-residue protein with a calculated mass of 372 kDa. The predicted protein was found to have no NH 2-terminal signal sequence but a single hydrophobic domain at the COOH terminus. These results indicate that the 372-kDa antigen is cytoplasmically disposed and anchored to the Golgi membrane by the COOH-terminal hydrophobic domain.