MCP structure. (A) Schematic diagram of protein structure. R69W mutation is in CCP 2. The A304V mutation is in the transmembrane domain. (B) Crystal structure of CCP 2 highlighting the location of R69W. (C) Helical wheel diagram of predicted segments and transmembrane representation by SOSUI (http://bp.nuap.nagoya-u.ac.jp/sosui) of A304V MCP mutation versus that of wild type. Yellow arrows indicate mutation of MCP at position 304 from alanine (left) to valine (right).