Identification and characterization of a novel siglec, siglec-7, expressed by human natural killer cells and monocytes.
We describe the characterization of sialic acid-binding Ig-like lectin-7 (siglec-7), a novel member of the siglec subgroup of the immunoglobulin superfamily. A full-length cDNA encoding siglec-7 was isolated from a human primary dendritic cell cDNA library. Siglec-7 is predicted to contain three extracellular immunoglobulin-like domains that comprise an N-terminal V-set domain and two C2-set domains, a transmembrane region and a cytoplasmic tail containing two tyrosine residues embodied in immunoreceptor tyrosine-based inhibition motif-like motifs. Overall, siglec-7 exhibited a high degree of sequence similarity to genes encoding CD33 (siglec-3), siglec-5, OBBP1/siglec-6, and OBBP-like protein and mapped to the same region on chromosome 19q13.3. When siglec-7 was expressed on COS or Chinese hamster ovary cells, it was able to mediate high levels of sialic acid-dependent binding to human erythrocytes and soluble sialoglycoconjugates, suggesting that it may be involved in cell-cell interactions. Among human peripheral blood leukocytes, siglec-7 was found to be present at low levels on granulocytes, intermediate levels on monocytes, and relatively high levels on a major subset of natural killer cells and a minor subset of CD8(+) T cells. Immunoprecipitation experiments indicated that siglec-7 is expressed as a monomer of approximately 65 kDa.
Nicoll
G
G
Medical Sciences Institute/Wellcome Trust Biocentre at Dundee Complex, Department of Biochemistry, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland.
Ni
J
J
Liu
D
D
Klenerman
P
P
Munday
J
J
Dubock
S
S
Mattei
M G
MG
Crocker
P R
PR
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D015214:Antigens, Differentiation, Myelomonocytic / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D015152:Blotting, Northern; D016466:CHO Cells; D019556:COS Cells; D002460:Cell Line; D002871:Chromosome Banding; D002874:Chromosome Mapping; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics; D006224:Cricetinae; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D005260:Female; D015870:Gene Expression; D018922:HL-60 Cells; D006801:Humans; D016130:Immunophenotyping; D017404:In Situ Hybridization, Fluorescence; D007694:Killer Cells, Natural / Q000276:immunology / Q000378:metabolism*; D037102:Lectins; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009000:Monocytes / Q000276:immunology / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D018076:DNA, Complementary; D037102:Lectins; D012333:RNA, Messenger; C402206:SIGLEC7 protein, human