This project is a biochemical analysis of components of the chemotactic and cell adhesion systems of the cellular slime mold Dictyostelium discoideum. The endogenous lectin discoidin will be localized using subcellular fractionation and fluorescence and electron microscopy techniques. Discoidin carbohydrate binding sites will be labeled with a photolabile galactoside and labeled peptides will be purified and sequenced. Multiple discoidin peptide chains will be structurally compared and each form will be used to select a specifically reactive antibody from a bank of monoclonal antibodies raised against all forms. The two classes of discoidin I binding sites on living cells (ionic and carbohydrate) will be further characterized and the carbohydrate-containing receptor will be purified. The detergent solubilized cAMP receptor will be further characterized as will the ATP-dependent receptor regulatory system. The folate deaminase and the folate chemotactic receptor of vegetative cells will be examined using binding assays and affinity labeling techniques. A previously identified intracellular cyclic nucleotide binding protein will be further characterized and purified.
