Analysis of the Interaction between hPFTAIRE1 and PLZF in a Yeast Two-hybrid System

hPFTAIRE1 is a Cdc2-related kinase family member. To search its substrates and regulatory proteins, hPFTAIRE1 was fused to LexA and used as a bait to screen a human brain LexA two-hybrid library. In this screening, seven hPFTAIRE1 interacting proteins, including promyelocytic leukemia zinc finger (PLZF), were obtained. The interaction between PLZF and hPFTAIRE1 was confirmed by β-galactosidase assay and Leu growth activity. PLZF encodes a transcription factor belonging to the POZ/BTB domain and Kruppel zinc finger (POK) family. The highly conserved POZ/BTB domain plays a critical role in protein-protein interaction. We deleted the POZ/BTB and Kruppel zinc finger domains, respectively, and observed the inter- action between hPFTAIRE1 and truncated PLZFs by liquid β-galactosidase activity assay. A weak interaction was detected between hPFTAIRE1 and PLZF. We also observed the interaction between PLZF and another Cdc2-related kinase, PCTAIRE1. A similar result was observed. The interaction between PLZF and hPFTAIRE1 or PCTAIRE1 was confirmed by co-immunoprecipitation assay in a yeast system. PLZF is a phosphoprotein and plays multiple roles during cell growth. Our results suggest that hPFTAIRE1 and PCTAIRE1 may play important roles in the functional regulation of PLZF.