title: Concanavalin A binding sites on the plasma membrane of leek stem protoplasts.
abstract: The binding of concanavalin A (con A) to leek (Allium porrum L.) stem protoplasts has been investigated using sequential treatment with con A and haemocyanin and using con A covalently linked to ferritin. Prefixed protoplasts were evenly labelled. Unfixed protoplasts showed a clustered distribution of label. Low temperature and lanthanum reduced the clustering. Bound con A was lost from unfixed protoplasts incubated for 5 h after treatment, but con A/haemocyanin was not bound to nascent wall materials. Prefixed protoplasts treated with wall-removing enzymes before labelling showed only a small reduction of con A binding. These results indicate that con A is bound to plasma membrane components, but that binding is reduced by competition of nascent wall precursors.
authors.affiliation: Laboratoire de Biologie Végétale, Cytologie Expérimentale, Ecole Normale Supérieure, 24 rue Lhomond, F-75231, Paris, France.
authors.forename: F A
authors.initials: FA
authors.lastname: Williamson