Figure 3.
FIG. 3. Conformational differences in the ATP-binding site
of Btk (cyan ribbons and cyan side chains) and Itk (green
ribbons and green side chains). Unphosphorylated and
phosphorylated Itk adopts a closed catalytic conformation of the
C-helix and
glycine-rich loop. In contrast, the glycine-rich loop of
unphosphorylated Btk blocks the ATP-binding site, which is not
consistent with inhibitor binding. The Itk gatekeeper residue,
Phe^435, and catalytically important residues are shown in
detail. Itk residue numbering is used unless specified.
C-helix and
glycine-rich loop. In contrast, the glycine-rich loop of
unphosphorylated Btk blocks the ATP-binding site, which is not
consistent with inhibitor binding. The Itk gatekeeper residue,
Phe^435, and catalytically important residues are shown in
detail. Itk residue numbering is used unless specified.