Sialic acid binding receptors (siglecs) expressed by macrophages.
Sialic acids are structurally and topographically well-suited to function as ligands in cellular recognition events. Sialoadhesin (Sn) is a sialic acid binding receptor uniquely expressed by macrophage subsets. It is a member of the immunoglobulin (Ig) superfamily with 17 extracellular domains. Sn is a prototypical member of the siglec family of sialic acid binding proteins, which includes CD22, myelin-associated glycoprotein, CD33, and siglec-5. These membrane proteins are involved in discrete functions in the hemopoietic, immune, and nervous systems. The sialic acid binding region of siglecs is localized within the membrane-distal, amino-terminal domain and in the case of Sn, it has been characterized in atomic detail by X-ray crystallography, nuclear magnetic resonance, and site-directed mutagenesis. Our studies on Sn indicate that this receptor is likely to function as a macrophage accessory molecule in a variety of cell-cell and cell-extracellular matrix interactions. CD33 and siglec-5 are also expressed on macrophage subsets as well as other myeloid cells. However, unlike Sn, the properties of these molecules indicate a predominant role in signaling functions rather than in cell-cell interactions.
Munday
J
J
Department of Biochemistry, University of Dundee, United Kingdom.
Floyd
H
H
Crocker
P R
PR
D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D006801:Humans; D037102:Lectins; D008264:Macrophages / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism; D011971:Receptors, Immunologic / Q000378:metabolism*; D063267:Sialic Acid Binding Ig-like Lectin 1
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D015815:Cell Adhesion Molecules; D037102:Lectins; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; C571166:SIGLEC1 protein, human; C114531:SIGLEC5 protein, human; D063267:Sialic Acid Binding Ig-like Lectin 1; D019158:N-Acetylneuraminic Acid