Evidence that a developmentally regulated glycoprotein is target of adhesion-blocking fab in reaggregating dictyostelium

Abstract

The target site of adhesion-blocking Fab in aggregating Dictyostelium discoideum cells is a plasma membrane glycoprotein of approximate molecular weight 82,000 (refs 1-3), which is no longer synthesized after aggregation, and disappears from the plasma membrane4,5. However, since cell adhesion remains important during later stages of differentiation6-8, presumably another protein(s) takes over its function. One candidate is a glycoprotein (molecular weight 95,000) whose synthesis commences at the tip stage and continues until the completion of development5,8. Both proteins are strongly antigenic4. When pseudoplasmodia ('slugs', a late developmental stage) are disaggregated and replated, the cells recapitulate the previous sequence of morphological changes much more quickly than before6-8, although the glycoprotein of molecular weight 82,000 is not resynthesized during reaggregation4,8. We report here that monovalent antibody (Fab) directed against slug plasma membranes inhibits reaggregation by binding to the glycoprotein of molecular weight 95,000 which thus seems to be involved in cell adhesion. © 1980 Nature Publishing Group.