FIG. 7.

Predicted three-dimensional structure of the N-terminal half of A3G highlighting residues that influence cytoplasmic localization. A3G residues 1 to 65 are colored light green. The conserved zinc-coordinating residues H65, E67, C97, and C100 are colored cyan and labeled (Zn²⁺). Residues within the first 60 amino acids whose mutation results in a mislocalization of A3G-NTD-GFP are highlighted in red, orange, and yellow according to the degree of mislocalization (>50%, 25 to 50%, or 10 to 25%, respectively). The previously reported CRS (2) is tan, and critical residues within this motif are indicated (F126 and W127). Surface and ribbon representations of the model structure are shown with secondary structures numbered according to the A3G-CTD structure from the N to the C terminus as β1-β2/2′ (not visible here)-α1-β3-α2-β4-α3-β5-α4-α5 (Fig. S1 in the supplemental material) (13). Two residues with a significantly altered localization pattern [L49W and ins(R42)] were not predicted to be on the same surface, but it is probable that these mutations perturb the protein's structure.