Labelling of concanavalin A sites on the plasma membrane of soybean protoplasts

Abstract

The plasma membranes of protoplasts from cultured soybean cells bind haemocyanin after treatment with concanavalin A. On unfixed protoplasts the binding sites were unevenly distributed. In thin section and in Pt/Pd replicas, the haemocyanin molecules were seen in clusters. After 16 hours incubation, the haemocyanin appeared in tighter clusters and newly synthesized cellulose microfibrils were present. In contrast, the protoplasts prefixed before concanavalin A treatment exhibited a very even distribution of haemocyanin. These observations are discussed in relation to membrane structure and the fluid mosaic model based on analogous studies of animal cells.