DEDICATION
ACKNOWLEDGEMENTSAbove all, I would like to thank my mentor, Brenda Schulman, for immersing me into the world of cutting-edge research and teaching me what it takes to keep doing a leading science. The training will serve me well always. I want to thank Brenda for creating a collaborative, informative and productive environment for doing sciencesboth in terms of recruiting fantastic people and providing great resources. Also, I would like to thank committee members: John Cox, Eric Enemark, Roderick Hori and Stephen White for their effort and the advices they put into guiding me through graduate school.I would like to thank the members of the Schulman lab for all that they have taught me and making this journey a fun one: Danny Scott for his insightful scientific questions and suggestions; Dave Duda for all the brilliant crystallography tips and tricks; David Miller for keeping the lab fully stocked and equipment always running; Hari Kamadurai for all the experiment guides over the years; Jing Wang and Masaya Yamaguchi for their help on projects we did together; Jeremy Frye for great advices towards experiments and structural softwares; Ryan VanderLinden for all the scientific discussion and suggestions; Nicholas Brown and Kuen-Phon Wu for the inspiring conversation and help; Randy Watson a fellow PhD candidate, for all the scientific (and nonscientific) discussion, advices sand being very helpful; Vladislav Sviderskiy for being helpful and for all the fun times. Manjeet Mukherjee and Yumei Zheng (a fellow graduate student), for sharing parts of the journey; Shelia Boezman for all the care, administrative support and activity organization (not forgetting the chocolates, candies and doughnuts); Jenny Olszewski, Shein Ei Cho and Omar Alsharif for being great lab mates and the fun time together.Additionally, my thanks are for: Billy Dye for the guidance with cloning and all the smart jokes; Steve Kaiser for all the scientific discussions and the insights to the career; Mathew "Matt-man" Calabrese for the taking the time to teach; Julie Monda, Alan "DDR" Deng and Steven Seyedin for spreading the joy and for being ever helpful.
ABSTRACTTetratricopeptide (TPR) repeats are a 34-residue helix-turn-helix motif that when repeated pack into a superhelical structure. TPR domains are frequently found mediating protein-protein interactions, often through a central groove. One protein complex bearing numerous TPR repeats is the Anaphase Promoting Complex (APC). The anaphasepromoting complex (APC) is a multi-subunit complex, which orchestrates mitotic cell cycles. APC is an E3 ligase in the ubiquitin cascade, and directs the 26S proteosome degradation of cell-cycle regulators. Throughout mitotic progression, proteins that are key regulators of the cell cycle are assembled with polyubiquitin chains by APC.One domain of the human APC is comprised of four related TPR proteins, APC8, APC6, APC3, and APC7, with each found in pairs. Crystal structures of some of these indicate that each has an N-terminal dimerization domain...