Hfx_cass5 contains domain-swapped dimers (PDB 3IF4).

<p><b>A.</b> Ribbon depiction of two domain-swapped chains, each coloured from N-terminus (blue) to C-terminus (red). <b>B.</b> Tetrameric organisation depicted in ribbon form (left panel), showing engagement between two dimers (green and blue), each comprising two chains. Side chain stacking of key contacting residues (Tyr28, Tyr30, Arg31 and Glu35) is depicted. Corresponding view of electrostatic surface is also shown (right), with deep cleft centrally positioned. <b>C.</b> Rotated view of electrostatic surface, positioned to emphasise narrow dimensions of this basic slot along one tetramer surface.</p>