Cell adhesion in transformed D. discoideum cells: expression of gp80 and its biochemical characterization

Dictyostelium discoideum amoebae were transformed with an expression vector for the gp80, a protein believed to mediate EDTA-resistant cell adhesion in developmental cells. Vegetative cells, that do not normally contain gp80, expressed the protein and this expression was correlated with the formation of cell-cell adhesions. These contacts exhibited minimal EDTA-resistance. Biochemical analyses of the protein synthesized by vegetative cells suggested that it is identical to that produced by aggregation-competent cells, including the presence of a glycolipid anchor. Additional experiments indicated that the anchor was insensitive to hydrolysis by exogenous (glycosly)phosphatidylinositol-specific phospholipase C [G)PI-PLCs) but was sensitive to the endogenous anchor degrading enzyme. This enzyme, initially described in aggregating cells (da Silva and Klein, Exp. Cell Res., in press) was found to be present also in vegetative amoebae.