Aim:To display the aggregation-prone ligand binding domain (LBD) of the hu-man peroxisome proliferator-activated receptor gamma (PPARγ) on the surface ofbacteriophages to establish an easy screening assay for the identification of PPARγligands.Methods:Plasmids were constructed for the expression of the PPARγLBD as a fusion to the N-terminus of the g3p protein of filamentous phage or theC-terminus of the capsid protein D (pD) of phage lambda.The fusion proteinswere expressed in E coli and solubility characteristics were compared.Polyclonalantibodies against the LBD as well as the pD protein were prepared for Westernblot analysis and phage capture assay.Results:The pD-LBD fusion protein waspartially soluble,whereas the LBD-g3p fusion protein was detected only in theinsoluble fraction.The pD-LBD fusion protein was efficiently incorporated inphage particles.Furthermore,the LBD was shown to be displayed on the surfaceof bacteriophage lambda.On average,the pD-LBD fusion protein accounted for28% of the total pD protein in the lambda head capsid.Conclusion:The hydro-phobic PPARγ LBD was expressed as a soluble form of fusion protein in E coli anddisplayed on the surface of bacteriophage lambda when it was fused to the lambdapD protein.The lambda pD fusion system could be used for improving the solu-bility of proteins that tend to form inclusion bodies when expressed in E coli.Thelambda phage particles displaying the LBD of PPARy may be of great value for theidentification of novel PPARγ ligands. Aim: To display the aggregation-prone ligand binding domain (LBD) of the hu-man peroxisome proliferator-activated receptor gamma (PPARγ) on the surface of bacteriophages to establish an easy screening assay for the identification of PPARγ ligands. Methods: Plasmids were constructed for the expression of the PPARγLBD as a fusion to the N-terminus of the g3c g3c of the capsid protein D (pD) of phage lambda. The fusion proteins were expressed in E coli and solubility characteristics were compared. Polyclonalantibodies The LBD as well as the pD protein were prepared for Western blot analysis and phage capture assay. Results: The pD-LBD fusion protein was partially soluble, but the LBD-g3p fusion protein was detected only in the insuluble fraction. The pD-LBD fusion protein was efficiently incorporated inphage particles. Stillmore, the LBD was shown to be displayed on the surface of bacteriophage lambda. On average, the pD-LBD fusion protein, for28% of the total pD protein in the lambda head capsid. Conlusion: The hydro-phobic PPARγ LBD was expressed as a soluble form of fusion protein in E coli and displayed on the surface of bacteriophage lambda when it was fused to the lambdapD protein. lambda pD fusion system could be used for improving the solu-bility of proteins that tend to form inclusion bodies when expressed in E. coli. lambda phage particles displaying the LBD of PPARy may be of great value for the identification of novel PPARγ ligands.