Identification and purification of a 55K polypeptide in Sjögren's syndrome A antigen

The Sjögren's syndrome A antigen (SS-A) purified by affinity chromatography from human spleen was shown to contain a major polypeptide with a mol. wt. of 55 000 daltons confirmed as SS-A by its reactivity with different anti-SS-A sera on affinity columns, immunodiffusion and the Western blot. A similar reactive polypeptide was demonstrated in extracts of rabbit liver, brain, spleen, kidney, lung and thymus.