Appukuttan PS. Terminal alpha-linked galactose rather than N-acetyl lactosamine is ligand for bovine heart galectin-1 in N-linked oligosaccharides of glycoproteins.
J Mol Recognit 2002;
15:180-7. [PMID:
12382235 DOI:
10.1002/jmr.573]
[Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Preference for the beta-anomer of galactose attributed to the bovine heart 14 kDa galectin-1 (BHL-14) was re-examined using natural glycoproteins and artificially glycosylated proteins as ligands. Endogenous glycoproteins co-purified with BHL-14 during its affinity chromatographic isolation contained oligosaccharides bearing terminal alpha-linked galactose (TAG) moieties and were superior even to laminin as ligands for homogeneous BHL-14 obtained by high pressure liquid chromatography. Artificially glycosylated proteins prepared by covalent attachment of melibiose to proteins and containing TAG moieties were ligands for BHL-14, unlike their lactose counterparts which contained beta-linked galactose. Enzymatic removal of TAG moieties from the following glycoproteins abolished their recognition by BHL-14: (i) endogenous glycoproteins co-purified with BHL-14; (ii) mouse laminin; and (iii) bovine heart glycoproteins recognized by peanut agglutinin. Modification of TAG in laminin using galactose oxidase also rendered the glycoprotein inert towards BHL-14. Desialylation of human IgG, bovine thyroglobulin or laminin failed to increase the affinity of BHL-14 for these glycoproteins. Since removal of TAG or of sialic acid moiety exposed LacNAc (Gal beta1-->4 GlcNAc) in these glycoproteins, these results indicated that TAG, rather than LacNAc, is a ligand for BHL-14 on N-linked oligosaccharide chains of glycoproteins. Ready recognition of human IgA and jacalin-binding human plasma glycoproteins and non-recognition of human IgG suggested that T antigen (Galbeta1-->3 GalNAc) may also be ligand for galectin-1.
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