A Frizzled like protein in Dictyostelium discoideum INAUGURAL-DISSERTATION zur Erlangung des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakultät der Universität zu Köln vorgelegt von Deenadayalan Bakthavatsalam aus Chennai, Indien Köln, 2004 Referees/Berichterstatter: Prof. Dr. Angelika A. Noegel Prof. Dr. Martin Huelskamp Date of oral examination: 10.02.2005 Tag der mündlichen Prüfung The present research work was carried out under the supervision of Prof. Dr. Angelika A. Noegel, in the Institute of Biochemistry I, Medical Faculty, University of Cologne, Cologne, Germany from Nov 2001 to Feb 2005. Diese Arbeit wurde von Nov 2001 bis Feb 2005 am Biochemischen Institut I der Medizinischen Fakultät der Universität zu Köln unter der Leitung von Prof. Dr. Angelika A.Noegel durchgeführt. Acknowledgements In the preparation of this doctoral thesis I gratefully acknowledge the contribution made by one and all, supervisors, colleagues, well-wishers and friends. First of all I would like to express my heartfelt gratitude to my supervisor Prof. Angelika Noegel for her diligent guidance and constant encouragement throughout the course of my study. She strove to seek the very best in me with her expertise and knowledge, which provided the backbone of this research.