Localization of the concanavalin A binding carbohydrate in Chlamydomonas flagella

Chlamydomonas flagella are shown to possess two zones of concanavalin A (ConA) binding carbohydrate. The first zone, distinguished by a requirement for a prolonged labelling period for visualization of fluorescein isothiocyanate (FITC)-ConA fluorescence, is localized in the flagellar coat. The second zone is characterized by a rapid FITC- and [125I]ConA labelling subsequent to disruption of the flagellar membrane, but is unaffected by reagents that act only on the flagellar surface coat. Electron microscopy and ferritin-ConA labelling indicate that this subsurface zone is localized between the flagellar membrane and axoneme in the space that we term the flagelloplasm. These results are used to suggest possible functions for ConA binding glycosyl residues in flagella.