(a) Overall structure of GTFA-ΔN (coloured domains) superposed on the crystal structure of GTF180-ΔN (grey; PDB entry 3klk
; Vujičić-Žagar et al., 2010). Colour scheme: GTFA-ΔN domain V (residues 745–791 and 1643–1763), red; domain IV (residues 792–925 and 1610–1642), yellow; domain B (residues 926–988, 1517–1554 and 1596–1609), green; domain A (residues 989–1234, 1382–1516 and 1555–1595), blue; domain C (residues 1235–1381), magenta. The three catalytic residues in domain A are shown in stick representation and the calcium ion (Ca2+) bound between domains A and B is shown as a green sphere. The largest differences between GTFA-ΔN and GTF180-ΔN are observed for domain V; the hinge between domains IV and V is indicated with asterisks (residues 793 and 1646). (b) Schematic domain arrangement of GTFA-ΔN. The first 740 residues (signal peptide and N-terminal domain) are not present in the crystallized construct. Each domain consists of two (N-terminal and C-terminal) stretches of polypeptide (the N-terminal stretches are more darkly coloured), with the exception of domain C.