Opening and Closing of the Catalytic Site
Opening Image: α/β cross-section of F1. The open (empty) β subunit is shown in gold.
The catalytic β subunit exists in two conformations, open and closed. In keeping with the convention for allosteric proteins, the unliganded form is called the T state, whereas the liganded form is designated the R state. Two β subunits are always in the closed or R state. One βR subunit is liganded to MgADP and Pi, the other to MgATP. The third β subunit, designated βT, does not have any ligands.
Let's examine the folding of the closed β subunit. Each subunit has three domains:
- β-barrel domain on top
- α/β domain in the middle
- α-helical domain at the bottom