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ACTIVATED LEUKOCYTE CELL ADHESION MOLECULE; ALCAM

Alternative titles; symbols

CD166

Gene map locus 3q13.1-q13.2

TEXT

CLONING

CD6 (186720) is a receptor expressed on T cells that is believed to be involved in cell adhesion interactions between thymocytes and thymic epithelial cells. Bowen et al. (1995) observed that a number of cell lines, including human thymic epithelial cells, expressed a putative CD6 ligand, which they purified using antibody affinity purification. From this purified CD6 ligand, they obtained amino acid sequences with significant homology to the chicken neural adhesion molecule BEN/SC-1/DM-GRASP. They then used PCR fragments of chicken BEN to screen human activated T-cell and HL60 cell cDNA libraries to obtain cDNA clones. This human CD6 ligand was named ALCAM, for 'activated leukocyte cell adhesion molecule.' The ALCAM gene encodes a 500-amino acid polypeptide with a secretory signal sequence and 5 immunoglobulin (Ig) domains. Northern blot analysis detected a 5.2-kb mRNA expressed by mitogen-activated leukocytes and a number of T-cell, B-cell, monocyte, and tumor-derived cell lines, but not by unactivated leukocytes. 30 PubMed Neighbors

GENE FUNCTION

Bowen et al. (1995) demonstrated that ALCAM is a CD6 ligand by showing that an ALCAM fusion protein bound to COS cells transfected with CD6.

Skonier et al. (1996) performed targeted mutagenesis on ALCAM and found that the residues constituting the CD6 binding site are clustered on one face of the N-terminal Ig domain of ALCAM. The authors observed that the sequences in this region are conserved across species and that this domain may be the preferred site for interactions of many cell surface Ig superfamily members and the diverse molecules with which they interact. 30 PubMed Neighbors

By immunoprecipitation analysis using a CD6 fusion protein, Joo et al. (2000) detected both CD166 and a novel antigen, 3A11, on epithelial and mesenchymal cells. Using FACS analysis, Saifullah et al. (2004) showed that both CD166 and 3A11 were expressed at different levels on a variety of epithelial and mesenchymal cell lines derived from thymus, skin, synovium, and cartilage. Expression of 3A11, but not CD166, was enhanced by IFNG (147570). Immunoblot analysis showed expression of a 130-kD 3A11 antigen and a 105-kD CD166 antigen on rheumatoid arthritis synovial fibroblasts. Confocal microscopy revealed coexpression of 3A11 and CD166 at the cell surface. Transfection of epithelial cells with CD166-specific small interfering RNA significantly decreased expression of CD166 without altering 3A11 antigen levels. Saifullah et al. (2004) concluded that 3A11 and CD166 are distinct CD6 ligands. They suggested that 3A11 may mediate interactions of synovial and epithelial cells with T lymphocytes. 30 PubMed Neighbors

MAPPING

By fluorescence in situ hybridization, they mapped the human ALCAM gene to chromosome 3q13.1-q13.2.

REFERENCES

1. Bowen, M. A.; Patel, D. D.; Li, X.; Modrell, B.; Malacko, A. R.; Wang, W.-C.; Marquardt, H.; Neubauer, M.; Pesando, J. M.; Francke, U.; Haynes, B. F.; Aruffo, A. :
Cloning, mapping, and characterization of activated leukocyte-cell adhesion molecule (ALCAM), a CD6 ligand. J. Exp. Med. 181: 2213-2220, 1995.
PubMed ID : 7760007

2. Joo, Y. S.; Singer, N. G.; Endres, J. L.; Sarkar, S.; Kinne, R. W.; Marks, R. M.; Fox, D. A. :
Evidence for the expression of a second CD6 ligand by synovial fibroblasts. Arthritis Rheum. 43: 329-335, 2000.
PubMed ID : 10693872

3. Saifullah, M. K.; Fox, D. A.; Sarkar, S.; Abidi, S. M. A.; Endres, J.; Piktel, J.; Haqqi, T. M.; Singer, N. G. :
Expression and characterization of a novel CD6 ligand in cells derived from joint and epithelial tissues. J. Immun. 173: 6125-6133, 2004.
PubMed ID : 15528349

4. Skonier, J. E.; Bowen, M. A.; Emswiler, J.; Aruffo, A.; Bajorath, J. :
Recognition of diverse proteins by members of the immunoglobulin superfamily: delineation of the receptor binding site in the human CD6 ligand ALCAM. Biochemistry 35: 12287-12291, 1996.
PubMed ID : 8823162

CONTRIBUTORS

Paul J. Converse - updated : 10/5/2006

CREATION DATE

Jennifer P. Macke : 2/4/1997

EDIT HISTORY

mgross : 10/24/2006
terry : 10/5/2006
jamie : 2/4/1997

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