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Multiple trkA proteins in PC12 cells bind NGF with a slow association rate
D S Hartman1, M McCormack, R Schubenel
1Pharma Division, F. Hoffmann-La Roche Ltd., Basel, Switzerland.
The Journal of Biological Chemistry
|December 5, 1992
Summary
Researchers identified novel forms of the nerve growth factor receptor (NGFR) trkA in PC12 cells. These findings reveal new insights into NGFR signaling pathways and their role in neurotrophin binding.
Area of Science:
- Neuroscience
- Cell Biology
- Molecular Biology
Background:
- PC12 cells express nerve growth factor receptors (NGFRs) p75NGFR and trkA (p140trk).
- NGF signaling is crucial for neuronal development and function.
Purpose of the Study:
- To identify and characterize novel forms of the trkA receptor in PC12 cells.
- To investigate the role of these novel trkA forms in nerve growth factor (NGF) binding and signal transduction.
Main Methods:
- 125I-mNGF affinity labeling to identify NGF-binding proteins.
- BS3 chemical cross-linking to detect protein complexes.
- Immunoprecipitation using p75NGFR-specific antisera.
- Analysis of protein molecular weights and phosphorylation status.
Main Results:
- Two additional trkA protein bands (220-kDa and 300-kDa) were identified beyond the canonical p140trk.
- The 220-kDa band represents trkA with alternate post-translational modification.
- The 300-kDa band suggests a trkA dimer formation.
- All identified trkA forms were phosphorylated upon NGF binding and exhibited similar NGF binding kinetics.
- All trkA forms bound brain-derived neurotrophic factor and neurotrophin-3.
Conclusions:
- PC12 cells express multiple forms of the trkA receptor, including modified and dimeric forms.
- These trkA variants are involved in NGF signal transduction and neurotrophin binding.
- The findings expand our understanding of trkA receptor complexity and its role in neuronal signaling.