Figure 2
From: Structural and evolutionary bioinformatics of the SPOUT superfamily of methyltransferases
'Perpendicular' and 'antiparallel' modes of dimerization observed among SPOUT enzymes, exemplified by TrmH (1v2x, left) and TrmD (1p9p, right). One monomer (indicated in green, shown on the top) is shown in the same orientation in both proteins, while the other one (indicated in blue, shown on the bottom) is rotated by about 90 degrees (TrmH) or 180 degrees (TrmD) with respect to the first one.