Lectin receptors on the plasma membrane of soybean cells. Binding and lateral diffusion of lectins

• Published in: Biochemistry (Easton) 1983-01, Vol.22 (16), p.3969-3975
• Main Authors: Metcalf, Thomas N, Wang, John L, Schubert, Karel R, Schindler, Melvin
• Format: Article
• Language: English
• Subjects: agglutinins; Biological and medical sciences; Cell Membrane - metabolism; Cell Membrane - ultrastructure; concanavalin A; Conformational dynamics in molecular biology; fluorescence; Fundamental and applied biological sciences. Psychology; Glycine max; Kinetics; lateral diffusion; Lectins - metabolism; Microscopy, Electron, Scanning; Molecular biophysics; Plant Lectins; Plants - metabolism; Protoplasts - metabolism; Protoplasts - ultrastructure; Receptors, Mitogen - metabolism; Species Specificity; Structure-Activity Relationship; wheat germ
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi00285a037

Protoplasts prepared from suspension cultures of root cells of Glycine max (SB-1 cell line) bound soybean agglutinin (SBA), concanavalin A (Con A), and wheat germ agglutinin (WGA). Binding studies carried out with 125I-labeled SBA, Con A, and WGA showed that these interactions were saturable and specific. Fluorescence microscopy demonstrated uniform membrane labeling. The mobility of the lectin-receptor complexes was measured by fluorescence redistribution after photobleaching. The diffusion constants (D) for SBA and Con A were 5 X 10(-11) and 7 X 10(-11) cm2/s, respectively. In contrast, WGA yielded a diffusion constant of 3 X 10(-10) cm2/s. Pretreatment of the protoplasts with either SBA or Con A resulted in a 6-fold reduction in the mobility of WGA (D congruent to 5 X 10(-11) cm2/s). The results suggest that the binding of SBA or Con A may lead to alterations of the soybean plasma membrane which, in turn, may restrict the mobility of other receptors.