Cell-specific glycoforms of sialoadhesin and CD45 are counter-receptors for the cysteine-rich domain of the mannose receptor.
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 (Mo) and B cell areas in the spleen and to subcapsular sinus Mo 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 Mo-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.
Martínez-Pomares
L
L
Sir William Dunn School of Pathology, Oxford University, Oxford OX1 3RE, Scotland. pomares@worf.molbiol.ox.ac.uk
Crocker
P R
PR
Da Silva
R
R
Holmes
N
N
Colominas
C
C
Rudd
P
P
Dwek
R
R
Gordon
S
S
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000737:chemistry; D006026:Glycoside Hydrolases / Q000494:pharmacology; D007128:Immunoglobulin Fragments / Q000378:metabolism; D037181:Lectins, C-Type; D017493:Leukocyte Common Antigens / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D011233:Precipitin Tests; D011485:Protein Binding / Q000187:drug effects; D020033:Protein Isoforms / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism; D011971:Receptors, Immunologic / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D063267:Sialic Acid Binding Ig-like Lectin 1; D013154:Spleen / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism; D013997:Time Factors
D007128:Immunoglobulin Fragments; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D008562:Membrane Glycoproteins; D020033:Protein Isoforms; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D063267:Sialic Acid Binding Ig-like Lectin 1; C571167:Siglec1 protein, mouse; D013431:Sulfates; D017493:Leukocyte Common Antigens; D006026:Glycoside Hydrolases; D003545:Cysteine