Cell surface oligosaccharide modulation during differentiation: III. Lectin affinity class distributions.
In previous studies we showed that the onset of the morphological phenotype of cellular senescence (IMR-90) in vitro is preceded by complex cell surface changes. Using fluorescently conjugated lectins these studies showed: (1) quantitative PDL-dependent decreases in cell surface mannosyl, galactosyl, and N-acetyl-glucosamine residues; (2) these changes were correlated with changes in ligand/lectin membrane mobility, suggesting a functional relationship for the quantitative changes. To further investigate the biological significance of these observations we have developed a synthetic ligand competition assay to analyze the lectin binding event itself. The results of these analyses show that: (1) the number of binding affinity class distributions is highly restricted; (2) the PDL-dependent mannosyl change is due to the loss of a high-affinity class distribution without significant change in the low-affinity site; and (3) PDL-dependent changes in both galactosyl and N-acetyl glucosamine binding events are the result of changes in the affinity class distributions. These results are interpreted in terms of the potential available energy to act as the basis for signal transduction at the cell surface.
Mann
P L
PL
Department of Anatomy, University of New Mexico, School of Medicine, Albuquerque 87131.
Swartz
C M
CM
Holmes
D T
DT
D001667:Binding, Competitive; D002241:Carbohydrates; D002454:Cell Differentiation; D002460:Cell Line; D002462:Cell Membrane / Q000648:ultrastructure*; D006801:Humans; D007700:Kinetics; D037102:Lectins; D009844:Oligosaccharides / Q000032:analysis*; D013329:Structure-Activity Relationship
D002241:Carbohydrates; D037102:Lectins; D009844:Oligosaccharides