The pGBKT7 vector expresses proteins fused to amino acids 1–147 of the GAL4 DNA binding domain (DNA-BD). In yeast, fusion proteins are expressed at high levels from the constitutive ADH1 promoter (PADH1); transcription is terminated by the T7 and ADH1 transcription termination signals (TT7 & ADH1). pGBKT7 also contains the T7 promoter, a c-Myc epitope tag, and a MCS. pGBKT7 replicates autonomously in both E. coli and S. cerevisiae from the pUC and 2 μ ori, respectively. The vector carries the Kanr for selection in E. coli and the TRP1 nutritional marker for selection in yeast. Yeast strains containing pGBKT7 exhibit a higher transformation efficiency than strains carrying other DNA-BD domain vectors (1).