Figure 4.

Three-Dimensional Modeling of Human PNPase

The structure of bacterial PNPase from E.coli (Protein Data Bank accession number 3CDI) is a homotrimer; the subunits are indicated by different colors (light red, green, and blue). The glutamate residue corresponding to Glu475 of human PNPase (red space-filling representation) forms a salt bridge to an arginine residue (blue spacefill) of the neighboring subunit (see also Figure S5). The pink dotted lines indicate unresolved parts of the structure.

(A) Top view along the trimer symmetry axis; all three salt bridges are indicated.

(B) Side view; only one of the salt bridges is shown.