Ⅰ. INTRODUCTION 1 Ⅱ. MATERIALS AND METHODS 5 2.1 Plasmid construct 5 2.2 Cell culture and transfection 5 2.3 Western Blot analysis 6 2.4 Protein expression and purification in mammalian cell 6 2.5 Negative stain TEM 7 2.6 Cryo-EM data collection and image processing 8 2.7 Protein expression and purification in bacterial cells 9 Ⅲ. RESULTS 14 3.1 Detergent screening and protein purification of mBEST1 14 3.2 Cryo-EM structures of mBEST1 17 3.3 Neck and Ca2+-clasp of mBEST1 and cBEST1 21 3.4 The aperture region of mBEST1 25 3.5 Cl- binding in mBEST1 26 3.6 The C-terminus of mBEST1 27 Ⅳ. DISCUSSION 32 Ⅴ. REFERENCES 35 Ⅵ. Abstract in Korea (요약문) 39
