Molecular cloning of a novel 97‐kd Golgi complex autoantigen associated with Sjögren's syndrome

Objective. To identify a Golgi complex autoantigen bound by Sjögren's syndrome (SS) autoantibodies. Methods. Serum from a patient with secondary SS and anti‐Golgi antibodies was used as a probe to isolate a complementary DNA (cDNA) insert from a HeLa cDNA library. Results. A 3.7‐kb cDNA encoding a 56‐kd recombinant protein was immunoprecipitated by the human anti‐Golgi serum and immune rabbit serum. Western blot analysis showed that the immune rabbit sera recognized a protein of 97 kd (golgin‐97), suggesting that the isolated clone contained a partial cDNA. The 5′ upstream sequence was obtained by rapid amplification of the cDNA ends. The complete cDNA contained 4,860 basepairs, encoding a protein with a calculated Mr of 88 kd. Antibodies to golgin‐97 were found in 12 (20%) of 60 sera known to have anti‐Golgi autoantibodies, and the majority of these sera (8 of 12, or 75%) were from patients who had secondary SS. Conclusion. Golgin‐97 is a unique Golgi complex antigen that appears to be a target of SS autoantibodies.