Figure 2.

aCPS and mCPS synthetase component domain structures. In both aCPS and mCPS the synthetase component is expressed as two separate subunits. The block diagrams compare the extent of the N and C subunits to domains N and C in eCPS (numbering based on eCPS sequence). In the structure figures, residues in the eCPS structure (PDB file 1BXR) that correspond to subunits N or C of aCPS or mCPS are highlighted in dark gray. Bound nucleotide analogs are shown in black spacefill representation. Although all three CPSs contain a separate glutamine amidotransferase subunit (GAT), it is omitted for clarity with the exception of eCPS GAT in the structure figure, where it aids in orientation.