mRNAs for the immobilization antigens of Paramecium

Immobilization antigens of stock 51 of Paramecium tetraurelia were subjected to electrophoresis in NaDodSO(4)/polyacrylamide gels. Type A is estimated to have a molecular size of 300,000 daltons; H is estimated to be 288,000, D to be 280,000, E to be 270,000, B to be 253,000, and C to be 250,000. Poly(A)(+)RNAs have been isolated from cells producing these antigens and subjected to electrophoresis in methylmercury gels. A major band is found to vary in mobility with antigenic type: Its position in preparations derived from paramecia synthesizing antigen A indicates a size of 8400 nucleotide residues; its position from paramecia synthesizing other antigens indicate H, 8200; D, 7900; E, 7500; B, 7600; and C, 7000. Because of the sizes and quantities of these RNAs, it is argued that they probably represent the mRNAs for the immobilization antigens. It is concluded that each immobilization antigen probably consists of a single polypeptide and that only one major serotype-determining mRNA is present in each antigenically different paramecium.