Molecular characterization of Ro(SSA) and La(SSB) proteins.

Ro(SSA) and La(SSB) proteins were characterized using human spleen extract as antigen and monospecific anti-Ro(SSA) and anti-La(SSB) sera. The antigens were partially purified by DEAE cellulose and Sephacryl chromatography, and then were electrotransferred to nitrocellulose sheets after SDS-PAGE electrophoresis. The anti-Ro(SSA) sera had reacted with a polypeptidic band of 58 kilodaltons (kDa), meanwhile the La(SSB) antisera reacted with 2 polypeptidic bands of 42 and 40 kDa. The molecular weight of the Ro(SSA) and La(SSB) proteins obtained by gel filtration chromatography was in agreement with the PAGE/electrotransfer results. These procedures are useful tools for the molecular analysis of the markers in the connective tissue diseases.