Analyzing the symmetrical arrangement of structural repeats in proteins with CE-Symm
Fig 5
Uneven stoichiometry as a consequence of internal symmetry.
The Bowman-Birk inhibitor from snail medic seeds (yellow) forms a complex with two bovine trypsin subunits (blue) in an uneven (A2B) stoichiometry and asymmetric assembly (2ILN). However, a 2-fold symmetry axis (red) can be identified in the complex when the internal symmetry of the inhibitor is taken into account, showing that the complex is equivalent to one with even (A2B2) stoichiometry.