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The adapter protein CrkL associates with CD34
D M Felschow1, M L McVeigh, G T Hoehn
1Johns Hopkins Oncology Center, Johns Hopkins University School of Medicine, Bunting-Blaustein Cancer Research Building, 1650 Orleans St., Baltimore, MD, USA.
Blood
|June 5, 2001
Summary
CD34, a protein crucial for hematopoietic stem cells, directly interacts with the CrkL adapter protein. This interaction occurs via CrkL's C-terminal SH3 domain, revealing new insights into CD34 signaling pathways.
Area of Science:
- Hematology
- Molecular Biology
- Cell Signaling
Background:
- CD34 is a cell-surface protein vital for lymphohematopoietic development and cell adhesion.
- Understanding the intracellular signals regulated by CD34 is crucial for elucidating its role in cell function.
Purpose of the Study:
- To identify proteins that associate with the intracellular domain of CD34.
- To elucidate the specific interactions between CD34 and intracellular signaling molecules, particularly adapter proteins.
Main Methods:
- Construction and use of glutathione-S-transferase (GST)-fusion proteins of the CD34 intracellular domain (GST-CD34i(full)).
- Co-immunoprecipitation assays to confirm in vivo interactions.
- GST-fusion protein precipitation assays to identify binding partners and domains.
Main Results:
- GST-CD34i(full) precipitated constitutively associated proteins of 39, 36, and 33 kDa, and an adhesion-associated 45-kDa protein.
- The 39-kDa protein was identified as CrkL, which was confirmed to associate with CD34 in vivo.
- CD34 was shown to bind the C-terminal SH3 domain of CrkL, with specificity distinct from CrkII.
Conclusions:
- CD34 directly couples to the hematopoietic adapter protein CrkL.
- This interaction is mediated by the C-terminal SH3 domain of CrkL.
- The findings reveal a novel signaling pathway involving CD34 and CrkL in hematopoietic cells.