Erratum: Forming and inhibiting PRT active sites

Nature Struct. Biol. 6, 502– 504 (1999).

Fig. 2 of this News and Views was printed in an incorrect orientation. The proper orientation is shown below. We regret any confusion this may have caused.

Fig. 2 Ligand binding to the PRT active site at different points in the catalytic cycle.Ligands from four structures are shown superimposed on the GPAT PRPP loop. Green, binary substrate complex (Mg-cPRPP from GPAT¹); red, ternary substrate complex (Mg₂-PRPP from trypanosomal HPRT²); blue, ternary product complex (ImmGP/Mg₂-PP_i from human HPRT³); yellow, binary product complex (GMP from human HPRT⁴). The green and red ligands show ribose in the 'down' position, the blue is 'intermediate', and the yellow is 'up'. Green, red and blue ligands are from closed-form PRT structures, and the yellow ligand is from an open-form structure. The catalytic metal site is below the pyrophosphate in this view; the second metal site is above. Protein carboxylate ligands to the second metal site are shown in pastel colors. Hydrogen bonds between the second metal site and purine base are shown as dashed lines.