has part ATP-binding cassette (ABC) transporter complex cobalamin transport complex vitamin B12-transporting BtuCDF complex Protein complex facilitating ATP-dependent cobalamin (vitamin B12) transport through inner cell membrane (periplasm to cytoplasm) in Gram-negative bacteria. In E. coli the system is composed of a periplasmic cobalamin-binding protein (BtuF), an integral membrane homodimer, BtuC, and a cytoplasmic ATP-binding homodimer BtuD. cellular_component bhm vitamin B12 transport complex 2013-09-12T14:20:19Z cobalamin-transporting BtuCDF complex GO:1990191 BtuCDF complex BtuCD complex