Cell-specific Glycoforms of Sialoadhesin and CD45 Are Counter-receptors for the Cysteine-rich Domain of the Mannose Receptor

• Published in: The Journal of biological chemistry 1999-12, Vol.274 (49), p.35211-35218
• Main Authors: Martínez-Pomares, L, Crocker, P R, Da Silva, R, Holmes, N, Colominas, C, Rudd, P, Dwek, R, Gordon, S
• Format: Article
• Language: English
• Subjects: Animals; Blotting, Western; Cell Line; Chromatography, Affinity; Chromatography, High Pressure Liquid; Cysteine - chemistry; Glycoside Hydrolases - pharmacology; Immunoglobulin Fragments - metabolism; Lectins, C-Type; Leukocyte Common Antigens - chemistry; Leukocyte Common Antigens - isolation & purification; Leukocyte Common Antigens - metabolism; Mannose-Binding Lectins; Membrane Glycoproteins - chemistry; Membrane Glycoproteins - isolation & purification; Membrane Glycoproteins - metabolism; Mice; Mice, Inbred BALB C; Precipitin Tests; Protein Binding - drug effects; Protein Isoforms - metabolism; Protein Processing, Post-Translational; Receptors, Cell Surface - chemistry; Receptors, Cell Surface - metabolism; Receptors, Immunologic - chemistry; Receptors, Immunologic - isolation & purification; Receptors, Immunologic - metabolism; Sialic Acid Binding Ig-like Lectin 1; Spleen - metabolism; Sulfates - metabolism; Time Factors
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.274.49.35211

We previously reported that CR-Fc, an Fc chimeric protein containing the cysteine-rich (CR) domain of the mannose receptor, binds to marginal zone metallophilic macrophages (Mø) and B cell areas in the spleen and to subcapsular sinus Mø in lymph nodes of naive mice (CR-Fc + cells). Several CR-Fc ligands were found in spleen and lymph node tissue lysates using ligand blots. In this paper we report the identification of two of these ligands as sialoadhesin (Sn), an Mø-specific membrane molecule, and the leukocyte common antigen, CD45. CR-Fc bound selectively to Sn purified from spleen and lymph nodes and to two low molecular weight isoforms of CD45 in a sugar-dependent manner. CR-Fc binding and non-binding forms of Sn, probably derived from CR-Fc + and CR-Fc − cells respectively, were selected from spleen lysates. Analysis of the glycan pool associated with the CR-Fc-binding form revealed the presence of charged structures resistant to sialidase, absent in the non-binding form, that could correspond to sulfated structures. These results confirm the identification of the CR region of the mannose receptor as a lectin. We also demonstrate that the same glycoprotein expressed in different cells of the same organ can display distinct sugar epitopes that determine its binding properties.