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. Author manuscript; available in PMC: 2016 Jan 1.
Published in final edited form as: Curr Protein Pept Sci. 2015;16(1):31–48. doi: 10.2174/1389203716666150213160438

Figure 5. Summary of glycan specificity of the MRH domain-containing proteins.

Figure 5

Top panel, Binding of glucosidase II β-subunit (GIIβ), OS-9, and XTP3-B to high mannose-type glycans is shown. The glycan binding specificity of XTP3-B remains unresolved, with recent studies indicating a preference for M9 glycan (asterisk-labeled bar) wheras other groups report binding to M5, M6 and M7 glycans. GlcNAc-1-phosphotransferase γ subunit’s ability to interact with specific glycan structures has not yet been determined. Bottom panel, Binding of MPRs to phosphorylated glycans. The CD-MPR and each of the three carbohydate binding domains of the CI-MPR recognize different populations of phosphorylated glycans. For simplicity, only the M6P (P) containing glycans are shown, with the phosphorylated mannose residue highlighted. M6P-GlcNAc-containing glycans have the identical structure, except with a phosphodiester at the analogous position as the phosphomonoester. Domains 1–3 and 9 preferentially bind M6P-containing glycans (grey bars), whereas domain 5 binds only M6P-GlcNAc-containing glycans (open bar). Both MPRs are unable to bind a M7 glycan containing a phosphomannosyl residue on the B (α1,3 linked mannose h) or C (α1,6 linked mannose j) arm. Residues are labeled as in Figure 1A: glucose (blue triangles), mannose (green circles) and GlcNAc (blue squares).