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Mapping of the linear site on the Fas/APO-1 molecule targeted by the prototypic anti-Fas mAb
1Microbiology and Tumor Biology Center, Karolinska Institutet, Stockholm, Sweden.
Abstract:
Fas/APO-1 is a member of the nerve growth factor/tumor necrosis factor (TNF) family of receptors and has been shown to mediate apoptotic cell death upon binding of specific mAb. We report here that the prototypic anti-human Fas mAb (clone CH-11) induces apoptosis by binding to a linear epitope present on the extracellular domain of the Fas/APO-1 protein. Synthetic peptides corresponding to this epitope blocked the apoptotic effect of the antibody in a susceptible Jurkat T cell line. Based upon the similarity between the Fas/APO-1 protein and the recently crystallized soluble TNF receptor type I, we generated a molecular model of Fas/APO-1, Our computer modeling indicates that the antibody binding region forms a hairpin loop on the surface of the Fas/ APO-1 protein. These findings further our understanding of the Fas/APO-1-mediated apoptotic signal and may provide a useful tool in future investigations of programmed cell death.
Insights
The anti-Fas antibody CH-11 triggers apoptosis by binding a linear epitope on the Fas/APO-1 receptor. Molecular modeling revealed this binding site forms a hairpin loop, aiding programmed cell death research.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- Fas/APO-1 is a receptor in the TNF family mediating programmed cell death.
- Specific monoclonal antibodies (mAbs) binding Fas/APO-1 can induce apoptosis.
Purpose of the Study:
- To identify the epitope on Fas/APO-1 recognized by the anti-Fas mAb CH-11.
- To understand the structural basis of Fas/APO-1-mediated apoptosis.
- To explore the potential of this epitope for future research.
Main Methods:
- Utilized synthetic peptides to map the antibody binding site.
- Employed molecular modeling based on structural similarities to TNF receptor type I.
- Tested the apoptotic effect of the antibody in Jurkat T cells.
Main Results:
- The prototypic anti-human Fas mAb (clone CH-11) binds to a linear epitope on the extracellular domain of Fas/APO-1.
- Synthetic peptides corresponding to this epitope inhibited the antibody-induced apoptosis.
- Molecular modeling suggested the antibody binding region forms a hairpin loop on the Fas/APO-1 protein surface.
Conclusions:
- The study elucidates the specific binding site and structural features involved in Fas/APO-1-mediated apoptosis.
- These findings enhance understanding of programmed cell death pathways.
- The identified epitope may serve as a valuable tool for future investigations into apoptosis.