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Human NKG2F is expressed and can associate with DAP12
Dae-Ki Kim1, Juraj Kabat, Francisco Borrego
1Receptor Cell Biology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Twinbrook II, 12441 Parklawn Dr, Rockville, MD 20852, USA.
Molecular Immunology
|May 14, 2004
Summary
The NKG2F protein is expressed in natural killer (NK) cells and may regulate cell activation by interacting with DAP12. Its precise function remains unclear, potentially involving unknown partners or competition with other receptors.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- The NKG2 family of C-lectin type molecules plays a crucial role in regulating natural killer (NK) and T cell functions.
- NKG2A/B acts as an inhibitory receptor, while NKG2C, -E/H associate with DAP12 as activation receptors, all pairing with CD94 and recognizing HLA-E.
- NKG2F is an orphan gene within this family, predicted to have unique structural features including a transmembrane domain, an ITIM-like sequence, and a truncated extracellular domain.
Purpose of the Study:
- To investigate the expression and function of the NKG2F protein in NK cells.
- To determine NKG2F's potential to associate with signaling molecules like DAP12 and its intracellular localization.
- To elucidate the signaling capacity of NKG2F, particularly the role of its ITIM-like motif.
Main Methods:
- Immunological assays to detect NKG2F protein expression in NK cells.
- Co-immunoprecipitation to assess association with CD94 and DAP12.
- Analysis of intracellular localization and assessment of tyrosine phosphorylation in the ITIM-like motif.
Main Results:
- NKG2F protein is expressed in NK cells, primarily localized to intracellular compartments, likely due to its inability to associate with CD94.
- NKG2F can associate with DAP12, indicating a potential for activation signaling.
- The ITIM-like motif of NKG2F did not show phosphorylation, suggesting it may be a non-functional or 'mock' ITIM.
Conclusions:
- NKG2F is an expressed protein in NK cells with the capacity to associate with DAP12, suggesting a role in cell activation signaling.
- Its intracellular localization and lack of functional ITIM phosphorylation point to a unique or regulatory function, possibly as a component of a novel receptor complex or through competition for DAP12.
- NKG2F may represent a vestigial gene product or a regulator of immune cell activation through interaction with DAP12 signaling pathways.