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The Polycomb-group protein ENX-2 interacts with ZAP-70
Motoyuki Ogawa1, Yoshiki Hiraoka, Sadakazu Aiso
1Department of Anatomy, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. motoana@sc.itc.keio.ac.jp
Immunology Letters
|February 26, 2003
Summary
Human ENX-2 acts as a signaling molecule in T cell receptor pathways. Its tyrosine phosphorylation by p56(lck) is crucial for interaction with zeta associated protein-70 (ZAP-70).
Area of Science:
- Immunology
- Molecular Biology
- Cell Signaling
Background:
- ENX-2 is a homologue of Drosophila Enhancer of zeste, a Polycomb-group protein involved in gene regulation.
- T cell receptor (TCR)-mediated signaling is critical for adaptive immunity.
Purpose of the Study:
- To investigate the role of human ENX-2 in TCR-mediated signaling.
- To elucidate the molecular mechanism of ENX-2 involvement in T cell activation.
Main Methods:
- Immunoprecipitation assays to detect protein interactions.
- Western blotting with anti-phospho-tyrosine antibody to assess protein phosphorylation.
- In vitro kinase assays using purified p56(lck).
Main Results:
- ENX-2 co-precipitated with zeta associated protein-70 (ZAP-70) in T cell lysates.
- ENX-2 was phosphorylated on tyrosine, dependent on lymphocyte protein tyrosine kinase p56(lck) activity.
- The interaction between ENX-2 and ZAP-70 was abolished in p56(lck)-deficient cells.
- In vitro kinase assays confirmed p56(lck) directly phosphorylates ENX-2 on tyrosine.
Conclusions:
- Tyrosine phosphorylation of ENX-2 by p56(lck) mediates its interaction with ZAP-70.
- ENX-2 functions as a signaling molecule in the T cell receptor pathway through this phosphorylation-dependent interaction.