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Interaction between Jak3 and Nucleosome Assembly Protein 1
Hong-Bin Ji1, Qi-Wei Zhai, Jin-Fang Zhu
1Shanghai Institute of Biochemistry, the Chinese Academy of Sciences, Shanghai 200031, China. sib203@sunm.shcnc.ac.cn
Abstract:
Tyrosine kinase Jak3 plays a critical role in the interleukin 2 IL-2 signaling because it not only participates the Jak-Stat pathway, but also interacts with unidentified signal transducers and regulates expression of some oncogenes such as c-fos and c-myc. Abundant evidence demonstrated that phosphorylated tyrosine was necessary for the interaction between two proteins. Therefore, in order to clarify the role of Jak3 in IL-2 signal transduction, the tyrosine-phosphorylation-involved yeast two-hybrid system was constructed and the N-terminal region JH3-JH7 of Jak3 was used as a bait to screen a peripheral blood cDNA library. About 50 double-positive colonies were obtained. Sequence analysis indicated that one of them was from nucleosome assembly protein 1 gene (Nap1), and encoded a protein of 392 amino acid residues. Two-hybrid system results demonstrated that interaction between Jak3 and Nap1 depended on the level of tyrosine phosphorylation. Furthermore, immunoprecipitation and Western blot experiments confirmed that Jak3 really interacted with Nap1 in murine pro-B lymphocyte BAF/BO3beta cells.
Insights
This study identifies nucleosome assembly protein 1 (Nap1) as a novel interaction partner for tyrosine kinase Janus kinase 3 (Jak3). Their interaction is dependent on tyrosine phosphorylation, revealing new insights into interleukin-2 (IL-2) signaling pathways.
Area of Science:
- Cellular Biology
- Molecular Biology
- Immunology
Background:
- Janus kinase 3 (Jak3) is crucial for interleukin-2 (IL-2) signaling via the Jak-Stat pathway.
- Jak3 interacts with unknown proteins and regulates oncogene expression.
- Protein interactions involving Jak3 are often mediated by tyrosine phosphorylation.
Purpose of the Study:
- To identify novel Jak3 interacting proteins involved in IL-2 signal transduction.
- To investigate the role of tyrosine phosphorylation in Jak3-mediated interactions.
Main Methods:
- Construction of a tyrosine-phosphorylation-dependent yeast two-hybrid system.
- Screening of a peripheral blood cDNA library using the JH3-JH7 region of Jak3 as bait.
- Confirmation of protein interactions using immunoprecipitation and Western blot.
Main Results:
- Approximately 50 positive colonies were identified.
- Nucleosome assembly protein 1 (Nap1) was identified as a Jak3 interacting protein.
- The interaction between Jak3 and Nap1 was confirmed to be dependent on tyrosine phosphorylation in murine pro-B lymphocyte cells.
Conclusions:
- Nucleosome assembly protein 1 (Nap1) is a novel binding partner for Janus kinase 3 (Jak3).
- The interaction between Jak3 and Nap1 is regulated by tyrosine phosphorylation.
- This finding provides new insights into the molecular mechanisms of IL-2 signaling.