Molecule of the Month: Vacuolar ATPase
Two linked molecular motors are used to pump protons across membranes.
Exploring the Structure
V-ATPase in Action
V-ATPases are complex molecular machines with many moving parts, so they have proven difficult to study. Currently, the most complete structures have been obtained by cryoelectron microscopy. The one shown here is from yeast, and researchers determined structures for three different rotational states of the complex (PDB entries 5vox, 5voy & 5voz). The image shown here is looking at the molecule from the bottom, showing rotation of the proton-pumping portion. To see the rotation of the whole molecule, click on the image for an interactive JSmol.
Topics for Further Discussion
- Try comparing the number of subunits in the ring of V-ATPases, V/A-ATPases and ATP synthase. What does this tell you about the number of protons needed for each ATP that is broken down or built by the molecule?
- Atomic structures have been determined for many fragments of V-ATPases, which were then used to help build the low-resolution models obtained from cryoelectron microscropy. You can search for “V-ATPase” to look at some of these atomic structures.
March 2018, David Goodselldoi:10.2210/rcsb_pdb/mom_2018_3