Figure 4.
Fig. 4. Ammonium recruitment site and substrate channel.
presumably
forms a hydrogen bond to the side chain of S208 on the
extracellular side of Amt-1 (at the top), stabilized by a interaction
with the side chain of W137. The hydrophobic channel leading to
the cytoplasmic side is blocked by F96 and F204, with the latter
having significantly elevated B factors, an indication of
structural flexibility. The N[ ]atoms of two conserved
histidine residues, H157 and H305, are in hydrogen-bonding
distance and their imidazole rings are almost perfectly coplanar.
presumably
forms a hydrogen bond to the side chain of S208 on the
extracellular side of Amt-1 (at the top), stabilized by a 
interaction
with the side chain of W137. The hydrophobic channel leading to
the cytoplasmic side is blocked by F96 and F204, with the latter
having significantly elevated B factors, an indication of
structural flexibility. The N[ 
]atoms of two conserved
histidine residues, H157 and H305, are in hydrogen-bonding
distance and their imidazole rings are almost perfectly coplanar.