Structure and function of parasite surface membranes—II. Concanavalin a adsorption by the cestode Hymenolepis diminuta and its effect on transport

Abstract

1. 1. Receptor sites for the lectin Concanavalin A (Con A) are discontinuously distributed on the tegument surface plasma membrane. The majority of these sites are located along the proximal shafts of the microtriches. 2. 2. Worms treated with Con A subsequently exhibit, to different degrees, reduced uptake of glucose, galactose, lysine, uracil and uridine. Con A had no significant effect on the influx of methionine or glycerol, at ambient concentrations of glycerol where its entry is predominantly by free diffusion. 3. 3. The inhibition of hexose transport by Con A is of the noncompetitive type. Adsorption of the lectin appears to effect the number and/or mobility of the carriers, rather than block the solute recognition site. 4. 4. It is suggested that the effect of Con A on the adsorption of various solutes is related to the spatial location of their transport loci relative to the binding sites for Con A in the tegument brush border.