Fig. 5
From: New insights into the molecular mechanism of the Rab GTPase Sec4p activation
a Superposition between Sec4pV29.GDP.Sec2p and Sec4pWT.phosphate.Sec2p using the Cα atoms of the Sec4p binding site of Sec2p (residues 100–120). The V29 mutant shows a slight shift in the active site. The P-loop, nucleotide and other regions of the protein shift for about 1 Å in the direction of Sec2p. This shift causes a slightly more closed conformation in comparison with the wild type complex Sec4pWT.phosphate.Sec2p. b Superposition between Sec4pV29.GDP.Sec2p and Sec4pWT.phosphate.Sec2p performed using the P-loop (Cα residues 26–33) of Sec4p. In this superposition the residue Ile50 of Sec4pV29 shifts toward the active site, coming very close to one of the waters that coordinate the magnesium ion. Waters are represented by red spheres. Residues that participate on the magnesium coordination are shown