Monoclonal antibody characterisation of slime sheath: the extracellular matrix of Dictyostelium discoideum.

Proteins can be extracted from the slime sheath of Dictyostelium discoideum slugs by denaturing agents. A subset of these proteins is also released by cellulase digestion of the sheath, implying that protein-protein and protein-cellulose interactions are involved in sheath protein retention. It seems probable that the cellulose-associated sheath proteins are also associated with the cellulose of mature stalk cells. Monoclonal antibodies directed against sheath demonstrate extensive sharing of antigenic determinants between sheath proteins and a limited degree of antigenic sharing between sheath and slug cell proteins. All of the proteins recognised by these monoclonal antibodies are developmentally regulated. These results are discussed in terms of the structure of the sheath and its possible role(s) in D. discoideum development.