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The seven-span transmembrane receptor CD97 has a cellular ligand (CD55, DAF)
J Hamann1, B Vogel, G M van Schijndel
1Department of Clinical Viro Immunology, Central Laboratory of the Netherlands Red Cross Blood Transfusion Service, University of Austerdam, The Netherlands.
The Journal of Experimental Medicine
|September 1, 1996
Summary
CD97, an immune cell protein, binds to decay accelerating factor (DAF, CD55) on red blood cells. This interaction is crucial for cell adhesion and offers new insights into complement regulation.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- CD97 is an immune cell surface protein belonging to the secretin receptor superfamily.
- It features a unique extended extracellular region with EGF domains and calcium-binding sites.
- Unlike typical peptide hormone receptors, CD97's function in cellular interactions was previously unclear.
Purpose of the Study:
- To investigate the molecular interactions and cellular binding capabilities of CD97.
- To identify the specific cellular ligand for the CD97 receptor.
- To elucidate the role of CD97 in cell adhesion processes.
Main Methods:
- CD97 expression in COS cells (CD97 transfectants).
- Adhesion assays using lymphocytes and erythrocytes with CD97 transfectants.
- Monoclonal antibody (mAb) selection and characterization to block adhesion.
- Testing adhesion with erythrocytes lacking decay accelerating factor (DAF, CD55).
Main Results:
- CD97-transfected cells demonstrated specific adhesion with lymphocytes and erythrocytes.
- A blocking mAb identified the binding site on decay accelerating factor (DAF, CD55).
- Erythrocytes deficient in DAF (CD55) did not adhere to CD97 transfectants, confirming specificity.
Conclusions:
- CD97 possesses the ability to bind cellular ligands, specifically decay accelerating factor (DAF, CD55).
- This interaction represents the first identified cellular ligand for a seven-span transmembrane (7-TM) receptor.
- The findings highlight CD97's role in cell adhesion and potential involvement in complement regulation.