This summer, I worked on purifying the Def1-PH complex with Professor Murakami and Kenneth Newman of the Murakami Lab. Def1 is a protein known to tag RNA Polymerase II for degradation in yeast. More recently, it has been shown to copurify with TFIIH, a transcription factor involved in transcription initiation. Interestingly, the PH domain of TFIIH resembles ubiquitin, hinting that Def1 may recruit TFIIH similarly to how it interacts with ubiquitin. Alphafold predictions show an interaction between the Cue domain of Def1 and the PH domain of TFIIH, and our protein construct recreates this interaction by covalently linking the respective domains of Def1 and TFIIH. By purifying and imaging this protein complex through X-Ray crystallography, we hope to better understand the function of Def1 and how it modulates TFIIH and transcription at large.