Consider the Remarkable Structure of the F1Fo ATP Synthase Shown

Short Answer

Consider the remarkable structure of the F1Fo ATP synthase shown in the following schematic drawing. Answer the following question(s) based on the structure.

-As seen from the F? head in the matrix, the rotation of the c ring is counterclockwise in the ATP-synthesis mode of the motor and clockwise in the ATP-hydrolysis mode of the motor. As shown in the above drawing, the "a subunit" (labeled 2) is part of the stator embedded in the membrane, and it forms the entry and exit sites for the protons that are bound by the rotating c ring. How do you think the two half-channels of the a subunit are arranged as seen from the c ring? Write down A or B from the following schematic diagram as your answer.