The protein content of an adaptor protein, STAP-2 is controlled by E3 ubiquitin ligase Cbl.

Signal transducing adaptor protein-2 (STAP-2) is a recently identified adaptor protein that contains pleckstrin and Src homology 2 (SH2)-like domains as well as a YXXQ motif in its C-terminal region. Our previous study in T cells demonstrated that STAP-2 influences FAK protein levels through recruitment of E3 ubiquitin ligase, Cbl, ...
to FAK. In the present study, we found that Cbl directly controls the protein levels and activity of STAP-2. STAP-2 physically interacted with Cbl through its PH and SH2-like domains. Small-interfering RNA-mediated reduction of endogenous Cbl restored STAP-2 protein levels. In contrast, over-expression of Cbl induced STAP-2 degradation. Importantly, Cbl-mediated regulation of STAP-2 protein levels affected Brk/STAP-2-induced STAT3 activation. These results indicate that Cbl regulates STAP-2 protein levels and Brk/STAP-2-mediated STAT3 activation.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Hela Cells, Humans, Jurkat Cells, Neoplasm Proteins, Phosphoproteins, Protein Structure, Tertiary, Protein-Tyrosine Kinases, Proto-Oncogene Proteins c-cbl, STAT3 Transcription Factor, Ubiquitination
Biochem. Biophys. Res. Commun.
Date: Jun. 26, 2009
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