Abstract
Localization and properties of concanavalin A-binding sites (CABS) on the cells of the clonal muscle cell, L6 were investigated by two methods. Using fluorescent concanavalin A (Con A), only occasionally could even faint fluorescence be detected on myoblasts in young cultures. As proli-feration proceeded, the intensity of fluorescence increased and became localized on the boundaries where the cells came into contact with each other. This distribution was not affected by the treatment with EGTA, triton X-100 or colchicine, suggesting that neither the Ca2+, lipid matrix nor the microtubule contributed to the maintenance of the distribution. Cytochalasin B (CB), however, caused the CABS to rearrange as well as morphological changes in the cells. Using Con A and hemocyanin, very low CABS densities were found on young myoblasts. In contrast to the results with fluorescent Con A, dense labelling was found on over the entire cell surface of myoblasts in confluent cultures. Many myotubes had CABS but densities varied from cell to cell. The effects of CB in localizing CABS were also observed by the hemocyanin method which demonstrated that most CABS on L6 cells were affected directly and/or indirectly by CB.
