Insights into DNA substrate selection by APOBEC3G from structural, biochemical, and functional studies
A) Loop 1 in A3GCTD-DNA complex (teal, coil representation) moves 3Å compared to apo A3GCTD (PDBID 3IR2, green)  to enclose the adenine in the -1 pocket. B) Comparison of the A3GCTD apo crystal structure (green; PDB ID 3IR2)  to the A3GCTD-DNA structure (teal). Residue W211 flips in to stack with the nucleotide and residue P210 moves toward the nucleotide as compared to the apo structures, while W285 and Y315 remain static. C) Deaminase activity assays on A3GCTD mutants show that mutating residues on loop 1 can disrupt the deaminase activity of A3G completely in the case of W211A or partially in the case of P210G.