The Interaction Between HGBP3 And NIK/HGK

A novel human guanylate-binding protein (GBP) hGBP3 was identified and characterized. Similar to hGBP1 and hGBP2, hGBP3 has the first two motifs of the three classical guanylate-binding motifs, GXXXXGKS (T) and DXXG, but lacks the N (T) KXD motif. E.coli expressed hGBP3 protein specifically binds to GTP. In situ hybridization and northern blot indicated hGBP3 is specifically expressed in brain with high levels in hippocampus and cerebellum. Using a yeast two-hybrid system, it was revealed that the N-terminal region of hGBP3 binds to the C-terminal regulatory domain of NIK/HGK, a member of group I GCK (germinal center kinase) kinases. This interaction was confirmed by in vitro GST pull-down and co-immunoprecipitation assays. Binding of hGBP3 enhanced the kinase activity of the NIK/HGK, and overexpression of hGBP3 in 293T cells activated NIK/HGK-mediated c-jun N-terminal kinase (JNK) activation. It was proposed that hGBP3 regulates JNK activation by interacting with the C-terminal of NIK/HGK. The interaction between ALEX3 and Dbl Zhidong Luan(cell biology) Directed by professor Gengxi HuMembers of the armadillo (arm) repeat families of proteins are implicated in 3中国科学院生物化学和细胞生物学研究所 博士学位论文 摘要 tumorigenesis, embryonic, and maintenance of tissue integrity. We characterized a unknown gene (GenBank GI: 7705237) ALEX3 in GenBank, encoding 379 amino acids. ALEX3 shares significantly homology with ALEX1 and ALEX2. The genes encoding ALEX1, ALEX2 and ALEX3 co-localize to the same region in Xq21.33-Xq22.2. ALEX3 transcripts are found in most human tissues examined. Using the two-hybrid method, we found that ALEX3 physically interacts with proto-oncogene Dbl. GST pull-down assay and co-immunoprecipitation experiment confirmed the two-hybrid screening results. Although the biological functions of the complex consisting of ALEX3 and Dbl are unknown, our results indicate that ALEX3 is a component of Dbl-Rho/Cdc42 pathway.