Other Lectins

Other Lectins 1. Phaseolus vulgaris (Red Kidney-bean) 

In the early 1900 s, Landsteiner and Raubitschek discovered the hemagglutinating properties of kidney-bean extracts.439 Dorset and Henley16 later used navy-bean extracts to separate cellular elements 

—Schematic Representation of the Tetrameric Structure of the Five Isolectins from Phaseolus vulgaris. [Each form consists of various proportions of L (N-terminal Ser) and R (N-terminal Ala) subunits. From Ref. 630. (Published by permission ofProc. Natl. Acad. Sci. (7.S.A.)] 

vulgaris lectins have now been isolated by affinity chromatography on columns of Sepharose conjugated with porcine thyroglobu-lin 149,154 an(j fetuin,156 both of which glycoproteins bind the lectin. 

In light of the evidence, it is difficult to reconcile it with a report that the RNA- and DNA-stimulating activity of Phaseolus vulgaris extracts is not due to proteins.719 

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An intriguing possibility is that the IDGFs could interact as lectins with the insulin receptor itself, which is already known to bind other lectins. Wheat germ... 

There is still some discordance about markers for ATI cells [17, 18]. Varieties of glycocalyx appear to be expressed in ATI versus ATII cells, which can be distinguished by the binding of specific lectins. Lycopersicon esculen-tum lectin, for example, appears to adhere specifically to the apical plasma membrane of ATI cells [19, 20], Other lectin markers that have been reported in AEC typing are Ricinus communis agglutinin, Erythrina cristagalli lectin, soybean lectin and Bauhinia purpurea agglutinin (all for the ATI phenotype),... 

CD31 (54), Factor Vlll-related antigen (55), and CD34 (56) cannot often be demonstrated in poorly differentiated vascular tumors. The use of the lectin Ulex europaeus agglutinin 1 (UEA-1) (57) is a more sensitive method to detect endothelial cells. Like other lectins, however, UFA-1 reacts with many other cell types. 

Many lectins combine preferentially with a single sugar structure, for example g-galactose or L-fucose. For some lectins the specificity is broader and includes several closely related sugars, e.g., D-man-nose, g-glucose and g-arabinose other lectins-interact only with complex carbohydrate structures such as those that occur in glycoproteins, glycolipids,... 

Another feature of the eel-serum specificity that is unlike that of other lectins is the existence of anomeric preference only within the L-fucose series.167,674 Thus, a-L-fucopyranosides are two to five times as efficient as inhibitors as their parent compounds, whereas their /3-L-glycosidically linked counterparts have half to one-third the effect. On the other hand, the anomers of methyl 3-O-methyl-D-fucopyranoside are of equivalent activity, being approximately twice as active as the parent saccharide. In the D series, over 90% of the binding energy is evidently accounted for by parts of the sugar molecule other than the anomeric carbon atom and the aglycon. 

Numerous other lectins have been isolated however, information regarding their physical and chemical properties and carbohydratebinding specificity is incomplete. We present here, short descriptions of several lectins that have interesting biological and carbohydratebinding properties. Although many of these substances are already being used in a variety of studies, it is probable that more-complete characterization will enhance their value considerably. 

Schmidt and co-workers have also immobilized the mannose derivatives to the commercially available glass slides under reductive amination or acylation conditions [167], Their study showed that the ConA interaction was in accordance with those obtained in aqueous solution and other immobilization methods, and non-specific protein binding to the functionalized glass slides was negligible. The same carbohydrate microarray plate could also be tested for other lectins, therefore the precious immobilized carbohydrates can be reused. 

Active and inactive AFGP tested at 100 /ig/ml starting concentration also failed to inhibit numerous other lectins as well as immune animal sera possessing various hemagglutinating specificities. 

Finally the presence of Mn and Ca, indispensible to the activity of concanavalin A, has been observed in a certain number of other lectins. 

Thio, L.L., Clifford, D.B. and Zorumski, C.F. (1993). Blockade of ionotropic quisqualate receptor desensitization in rat hippocampal neurons by wheat germ agglutinin and other lectins. Neuroscience 52 35-44. 

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