Replication protein a 32 kDa subunit (RPA p32) binds the SH2 domain of STAT3 and regulates its transcriptional activity.
STATs (signal transducers and activators of transcription) are transcription factors that contain SH2 domains and are activated by tyrosine phosphorylation in response to cytokines and growth factors. Replication protein A (RPA) is a heterotrimeric complex that consists of three subunits, p70, p32 and p11, and has important functions in DNA replication and metabolism. Here, we present evidence that the RPA p32 subunit binds specifically to the SH2 domain of STAT3 in a phosphotyrosine-independent manner. We confirm their protein-protein interactions by yeast 2-hybrid analyses and in vitro binding assays using recombinant proteins generated from bacteria and in vitro translation. We also show that STAT3 binds to RPA p32 in vivo by conducting co-precipitation experiments. As the SH2 domain is highly involved in the tyrosine phosphorylation and the transcriptional activity of STAT3, over-expression of RPA p32 correspondingly augmented growth factor-stimulated tyrosine phosphorylation and transcription activities of STAT3.
Kim
J
J
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Kusong-dong, Yusong, Taejon, 305-701, Korea.
Kim
D
D
Chung
J
J
D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D008156:Luciferases; D051379:Mice; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D051716:Replication Protein A; D050796:STAT3 Transcription Factor; D015534:Trans-Activators / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D020798:Two-Hybrid System Techniques; D018909:src Homology Domains
D004268:DNA-Binding Proteins; C497167:RPA1 protein, human; D011993:Recombinant Fusion Proteins; D051716:Replication Protein A; C497168:Rpa1 protein, mouse; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C494087:Stat3 protein, mouse; D015534:Trans-Activators; D019000:Phosphotyrosine; D004815:Epidermal Growth Factor; D004247:DNA; D008156:Luciferases