Figure 8.

The NC interface and helix α0 (PB1). Superposition of an NC-interface dimer of SEPT2 (PDB entry 2qa5; red) with SEPT3α0G–GDP (PDB entry 4z54; blue). The overlay has been performed on only one of the two subunits (left). Helix α0 of SEPT2 (yellow) is buried within the open NC interface. If the interface were to close such as to occupy a position equivalent to that shown for SEPT3 (closed conformation) a steric clash would occur between α0 and α5 of the neighbouring subunit (green circle). As a consequence α0 would be expelled from the interface. Shown in purple is the position it occupies in the B chain of SEPT3α0G–GDP.