Phospholipid polar head group manipulation modulates concanavalin A agglutinability of LM fibroblasts.
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abstract
The effect of phospholipid polar head group manipulation in LM fibroblasts on fluoresceinylconcanavalin A binding, concanavalin A mediated hemadsorption, and concanavalin A mediated agglutination was determined. Choline analogues (N,N-dimethylethanolamine, N-methylethanolamine, and ethanolamine) were rapidly incorporated into LM plasma membrane phospholipids (35.1, 33.2, and 41.0 mol %, respectively). There were no changes in phospholipid fatty acid composition, sialic acid content, or membrane biophysical properties (characteristic break temperatures in Arrhenius plots and rotational correlation time of 1,6-diphenyl-1,3,5-hexatriene). The binding affinity of one of the two concanavalin A binding sites was doubled by all analogues tested. In addition, the concanavalin A mediated hemadsorption of sheep red blood cells and the concanavalin A mediated selfagglutinability of LM cells were doubled by choline analogue supplementation. Arrhenius plots of concanavalin A mediated agglutinability showed temperature break points for choline-fed cells at 24.3 and 33.1 C. In contrast, N,N-dimethyl-ethanolamine-, N-methylethanolamine-, and ethanolamine-supplemented cells had the following sets of break points: 18.3 and 27.6 C, 10.7 and 20.1 C, and 5.3 and 17.4 C, respectively. The data are thus consistent with a direct correlation between lectin agglutinability characteristics and plasma membrane phospholipid polar head group composition. In addition, since the temperature break points of concanavalin A agglutinability were decreased by choline analogue supplementation while the biophysical temperature break points were not, one could hypothesize that the concanavalin A receptors may reside in specialized fluid domains within the LM plasma membrane. 1982, American Chemical Society. All rights reserved.
