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. 2002 Jul 3;99(15):10042–10047. doi: 10.1073/pnas.142005099

Figure 3.

Figure 3

VWF glycosylation deficiencies and multimer formation. Alterations in lectin binding are compared with results obtained by using purified sialidase treatment (*; see Methods). (A) RCA-I lectin binding to plasma-derived VWF from wild-type and ST3Gal-IV mutant mice indicates increased exposure of terminal β-linked Gal on VWF from both heterozygous and homozygous mutant samples. Reduced Ricin binding to VWF from ST6Gal-I-deficient mice was observed. (B) ECA-I lectin binding to Galβ1–4GlcNAc- termini on VWF is increased in mice heterozygous or homozygous for ST3Gal-IV gene mutation. Absence of ST6Gal-I also results as expected in increased ECA binding to VWF. (C) SNA lectin binding to VWF is eliminated in ST6Gal-I deficiency, as expected, but increased in ST3Gal-IV deficiency. (D) PNA lectin binding to Galβ1–3GalNAc- is unaltered on VWF glycans from ST3Gal-IV mutant mice. (E) Possible N-glycan branch termini structures of wild-type and mutant VWF. Wild-type VWF bears highly sialylated N-glycan branches with both α3- and α6-linked sialic acids. Absence of ST6Gal-I eliminates only α6-linked sialic acid, although a partial compensation by ST3Gal-IV may occur (lightly shaded sialic acid). Separately, ST3Gal-IV deficiency exposes ECA-reactive Galβ1–4 GlcNAc termini and may also expose the Galβ1–3GlcNAc- disaccharide. Partial compensation (shaded sialic acid linkage) by ST6Gal-I occurs, whereas no sialyltransferase exists that can add α6 linkages to Galβ1–3GlcNAc-. However, some degree of α3 sialylation of Galβ1–3GlcNAc- may occur (shaded sialic acid). No changes occur in the sialylation of the Core 1 O-glycan Galβ1–3GalNAc-. (F) Multimer analysis of plasma VWF from wild-type and ST3Gal-IV mutants indicates normal multimer formation in mutant samples. Data are representative of three separate experiments. Lectin binding in A–C was quantitated by ELISA and plotted as the ratio of lectin binding per unit of VWF antigen (see Methods). Data in A–C are means ± SEM as derived from analyses of 12 or more mice of each genotype in each assay. Saccharide symbols: GlcNAc, black square; GalNAc; open square; Gal, black circle; sialic acid, black diamond.