<正>Objective:To screen the proteins interacting with the Treg specification factor forkhead box protein P3 （FOXP3） by yeast two-hybrid system.Methods:Human FOXP3 gene was amplified by nest RT-PCR from peripheral blood mononuclear cells （PBMC） and inserted into plasmid pGBKT7 to construct the bait vector

then the self-activation and toxicity of the bait vector in host yeast strain AH109 were observed.Thereafter

a human liver cDNA library was screened by the bait vector.The positive clones were selected out by nutrient-deficient culture and back-hybridizing.The sequences from the candidate positive clones were blasted and analyzed by bioinformatics methods.Results:The constructed bait vector encoding FOXP3 was found no self-activation and toxicity in yeast AH109.Three proteins which interacted with FOXP3

including tumor protein D52

splicing factor 3b subunit 1 and hypothetical protein

were identified.Conclusion:Three new candidate proteins interacting with FOXP3 are selected out by this yeast two-hybrid system and library

which may facilitate the further study of FOXP3 in Treg.