Sialoadhesin, a macrophage sialic acid binding receptor for haemopoietic cells with 17 immunoglobulin-like domains.
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.
Crocker
P R
PR
Imperial Cancer Research Fund Laboratories, John Radcliffe Hospital, Headington, Oxford, UK.
Mucklow
S
S
Bouckson
V
V
McWilliam
A
A
Willis
A C
AC
Gordon
S
S
Milon
G
G
Kelm
S
S
Bradfield
P
P
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001854:Bone Marrow Cells; D002240:Carbohydrate Sequence; D015815:Cell Adhesion Molecules / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D003001:Cloning, Molecular; D004912:Erythrocytes / Q000502:physiology; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry; D008264:Macrophages / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011971:Receptors, Immunologic / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D063267:Sialic Acid Binding Ig-like Lectin 1
D015815:Cell Adhesion Molecules; D007136:Immunoglobulins; D008562:Membrane Glycoproteins; D011971:Receptors, Immunologic; C571166:SIGLEC1 protein, human; D063267:Sialic Acid Binding Ig-like Lectin 1; C571167:Siglec1 protein, mouse