The multiple subunits of discoidin I are encoded by different genes

The translation product encoded by the mRNA complementary to a previously described plasmid termed pDd 8.1.2. (Williams et al., 1979) comigrates on SDS gels with discoidin I, a developmentally regulated lectin of Dictyostelium discoideum. This translation product also reacts specifically with an antiserum raised against purified discoidin. Two-dimensional gel analysis revealed that discoidin I consists of two polypeptides which we designate as discoidin Ia and discoidin Ib. Discoidin Ib sometimes migrates as a diffuse spot and sometimes as two barely resolved spots. It is possible, therefore, that discoidin Ib is itself a mixture of two polypeptides which display very similar electrophoretic behavior. We find that pDd 8.1.2. DNA hybridizes preferentially with the mRNA encoding discoidin Ia, suggesting that discoidin Ia and discoidin Ib are the products of different genes.