Our long term goals are to understand mechanisms by which glycoconjugates contribute to intracellular recognition and cohesion in morphogenetic processes, using aggregation of amoebae of Dictyostelium discoideum as the model, hypothesizing that specific glycans implicated in this cohesion are part of a recognition and docking system. Major objectives include: (1) Structural analysis of the glycans and similar but inactive species, to identify features required for biological activity. (2) Demonstration of direct cell adhesion to glycoconjugate-coated surfaces. (3) Tests of the hypothesis that the glycans are the sole basis for cohesion during aggregation, by perturbation with glycans and analogs, antibodies to the glycans and chemical modifications. (4) Investigation of cohesion, aggregation and biochemical defects in conditional glycosylation mutants, to test the hypothesis that failure to generate the glycans will prevent morphogenesis. (5) To examine whether other molecules also contribute to cohesion by multiple perturbant experiments. (6) Use of antibody probes to identify and isolate glycoproteins which carry the active glycans, to test the hypothesis that they carried by a number of distinct glycoproteins. (7) Identification and isolation of receptors for the glycans, by ligand binding, affinity fractionation and photoaffinity labelling, and determination of whether the recognition mechanism is homophilic or heterophilic.
