We have previously reported the purification of Sm and RNP
antigens from goat liver and identified two
polypeptides of molecular weights 70 and 80-90 kd as RNP specific and of 14 and 30 kd as Sm specific. In this communication the effect of
ribonuclease and
trypsin on Sm and RNP
antigens was studied at the
polypeptide level. We found that the RNP
antigenic determinant polypeptides of 70 and 80-90 kd are lost as a result of such treatment, whereas there is no effect on the Sm-specific 14- and 30-kd
polypeptides. The role of
RNA in the antigenicity of Sm and RNP was studied by dissociation and reconstitution studies. The
antigens were fractionated into
protein and
RNA and the individual fractions were tested for Sm and RNP activity by counterimmunoelectrophoresis (CIE) and
enzyme-linked
immunosorbent assay (ELISA). The
RNA fraction did not react alone with anti-Sm and anti-RNP sera with either of the assays. Conversely when the
protein fraction was tested by CIE, only Sm antigenicity was detectable. In the ELISA both Sm and RNP activities were demonstrated in the
protein fraction. These results show that the presence of
RNA is important in the immunoprecipitation reactions involving only RNP
antigen, whereas Sm activity is independent of
RNA. In addition, when the reaction is carried out by an assay involving primary antigen-antibody reaction (e.g., ELISA), RNP
antibodies react with
protein fractions alone, without the presence of
RNA. We also report the
glycoprotein nature of Sm-specific
polypeptides.(ABSTRACT TRUNCATED AT 250 WORDS)