Selective loss of wheat germ agglutinin binding to agglutinin-resistant mutants of Chinese hamster ovary cells.

Abstract

The binding of 125I-labeled wheat germ agglutinin (WGA) to parental and 3 distinct WGA-resistant Chinese hamster ovary cell lines possessing modified cell surface carbohydrate structures was examined over a 106-fold range of WGA concentrations. The Scatchard plot for WGA binding to parental cells was complex and exhibited positively cooperative binding at the high affinity sites. One of the WGA-resistant mutants (WgaRIII) was apparently not altered in its WGA-binding ability compared with parental cells. Of the WGA-resistant lines (WgaRI) and WgaRII) had distinct alterations in their WGA-binding properties specific to certain regions of the binding curve. Neither appeared to be affected in either the highest or lowest affinity regions of the binding curve. Lectin-resistant cell mutants altered in specific lectin-binding sites at the cell surface provide a direct approach to analysis of the complex binding parameters that characterize the interaction of WGA with the plasma membrane.