Immunochemical studies on the combining sites of Forssman hapten reactive hemagglutinins from Dolichos biflorus, Helix pomatia, and Wistaria floribunda

Abstract

The lectin of Dolichos biflorus, a hemagglutinin previously considered to be blood group A specific, is now found to react much more strongly with the terminal disaccharide unit [alpha DGalNAc(1 leads to 3) beta DGalNAc] of the Forssman antigenic determinant. In contrast, the relative reactions of the lectins of Helix pomatia (which also agglutinates A erythrocytes) and Wistaria floribunda (which agglutinates A, B, and O erythrocytes) with the Forssman pentasaccharide were substantially weaker than that of Dolichos biflorus. The combining site of the lectin of Helix pomatia has a broader affinity for terminal 2-acetamido-2-deoxy-alpha-D-galactopyranose (alpha DGalNAc) residues than does that of Dolichos biflorus. The reactions of the lectin with terminal alpha DGalNAc units are strongly dependent on the nature of the aglycon and remain ill defined. The lectin may also react with appropriately presented terminal 2-acetamido-2-deoxy-beta-D-glucopyranose units. The broad affinity of the lectin of Wistaria floribunda which reacts both with a range of blood group specific glycoproteins (A, B, H, Lea, and Leb) and with non blood group glycoproteins [Sugii, S., & Kabat, E.A. (1980) Biochemistry 19, 1192-1199] appears best assigned to a combining site that favors pauci- or multivalent cooperative effects of clustered terminal beta-D-galactopyranose units. An attempt is made to rationalize certain of the inhibition data in terms of topographical features at the surfaces of the carbohydrate structures which are considered compatible for binding within essentially hydrophobic combining sites.

Lectin-Binding Glycoconjugates in the Subfornical Organ of the Rat

“…regions of this organ. DBA exhibits a specificity towards terminal Nacetylgalactosamine of 0-glycosidically linked oligosaccharides (Baker et al, 1983). UEA-1 specifically reacts with a-Fucose at a branch or terminal position of oligosaccharides (Alroy et al, 1988).…”

Cosmc is an essential chaperone for correct protein O-glycosylation

“…First, we analyzed total glycoproteins before and after treatment with either sialidase (S), sialidase plus O-glycanase (O), which is specific for releasing the nonsialylated T antigen, or N-glycanase (P), which can release all types of N-glycans. Helix pomatia agglutinin (HPA) (8) binds to the Tn antigen control and many glycoproteins in the Cosmc −/y ES cells, but did not bind glycoproteins from WT cells (Fig. S2A), showing that loss of Cosmc results in expression of the Tn antigen on many different glycoproteins.…”

Human Tumor Antigens Tn and Sialyl Tn Arise from Mutations inCosmc

“…To further explore mutations in Cosmc associated with Tn antigen expression, we examined two melanoma cell lines, LOX and FEMX-I (21,22). LOX cells, derived from a male patient (22), were previously shown to be stained by HPA (23), a lectin that specifically recognizes a-GalNAc residues as in the Tn antigen (24). Interestingly, HPA binding correlated with experimental lung metastases in athymic nude mice (16).…”