Sialoadhesin, a macrophage sialic acid binding receptor for haemopoietic cells with 17 immunoglobulin-like domains.

Abstract

Sialoadhesin is a macrophage‐restricted adhesion molecule of 185 kDa that mediates sialic acid‐dependent binding to cells. It is expressed strongly by macrophages in lymphoid and haemopoietic tissues where it is likely to mediate cell‐cell interactions. Here we report the molecular cloning of murine sialoadhesin and show that it is a new member of the immunoglobulin (Ig) superfamily with 17 Ig‐like domains. COS cells transfected with a cDNA encoding full‐length sialoadhesin bound mouse bone marrow cells in a sialic acid‐dependent manner. Alternatively spliced cDNAs, predicting soluble forms of sialoadhesin containing the first three or 16 Ig‐like domains of sialoadhesin, were expressed in COS cells and the respective proteins purified. When immobilized on plastic, the 16‐domain form bound cells in a sialic acid‐dependent manner, suggesting that sialoadhesin can function in both secreted and membrane‐bound forms. The most similar proteins in the database were CD22, myelin‐associated glycoprotein, Schwann cell myelin protein and CD33. Like sialoadhesin, CD22 mediates sialic acid‐dependent cell adhesion. The sequence similarity of sialoadhesin to CD22 and related members of the Ig superfamily indicates the existence of a novel family of sialic acid binding proteins involved in cell‐cell interactions.

Differences in the constitutive and SIV infection induced expression of Siglecs by hematopoietic cells from non-human primates

“…It is the largest transmembrane member of the immunoglobulin super family (IgSF) with an extracellular domain made up of 17 immunoglobulin domains. Since it lacks tyrosine binding signaling motifs within its cytoplasmic domain and this domain is poorly conserved, it is likely that its primary function is more to serve as a binding partner for appropriate ligands and involved in cell adhesion and functions such as serving as a phagocyte receptor [42]. It has also been implicated in influencing T cell function and activation [43].…”

Interactions between Schwann cells and macrophages in injury and inherited demyelinating disease

“…Sialoadhesin (Sn), also designated Siglec-1 or CD169, is the prototypic member of the siglec family of sialic acid binding Ig-like lectins (Crocker et al, 1994). Other members of this family are CD22, MAG.…”

Expression, crystallization, and preliminary X-ray analysis of a sialic acid-binding fragment of sialoadhesin in the presence and absence of ligand

“…It is expressed only on resident macrophage subpopulations (Crocker et al, 1994), and cell binding studies have shown that, among hemopoietic cells, it binds preferentially to granulocytes . In the bone marrow, Sn is found selectively at contact sites with developing myeloid cells (Crocker et al, 1990(Crocker et al, , 1991, and it has been suggested that, in lymphoid tissues, it acts as a lymphocyte adhesion molecule (Van den Berg et al, 1992).…”

“…In the bone marrow, Sn is found selectively at contact sites with developing myeloid cells (Crocker et al, 1990(Crocker et al, , 1991, and it has been suggested that, in lymphoid tissues, it acts as a lymphocyte adhesion molecule (Van den Berg et al, 1992). On the basis of sequence analysis, Sn has been shown to be a member of the immunoglobulin superfamily (IgSF) (Williams & Barclay, 1988;Williams et al, 1989) consisting of 17 immunoglobulin-like domains, a membrane-spanning helix, and a short cytoplasmic domain (Crocker et al, 1994). The immunoglobulin domains are arranged in a linear array made up of 16 C2-set domains and one N-terminal, membrane distal, V-set domain.…”

“…Site-directed mutagenesis studies on the N-terminal V-set domain located a number of residues, predicted to lie in a discrete region on the surface of the GFCC'C p sheet, that were thought to form the sialic acid-binding site (Vinson et al, 1996). It has been suggested that the large number of subsequent domains may extend the sialic acid-binding site away from the plasma membrane to minimize &-interactions with oligosaccharides in the macrophage glycocalyx (Crocker et al, 1994).…”