Fig. 4.
Sequence of events in VO assembly. (A) Vma12-22p binds a complex containing the c ring, subunit d, and Vma21p. (B) Vma12p recruits subunits a, e, and f to the rest of VO. (C) The c ring in VO relaxes to its preferred orientation, releasing Vma12-22p. Vma21p ensures VO assembly intermediates are retrieved to the ER membrane. (D) Vma21p accompanies the fully assembled VO to the Golgi membrane. (E) V1∆C and subunit C bind VO and initiate rotary catalysis. (F) Rotation of the c ring releases Vma21p, which travels back to the ER membrane, leaving functional V-ATPase in the Golgi membrane (Movie S1).