CagF binds several domains of CagA. Isothermal titration calorimetry binding curves of CagFWT titrated against CagA1055–1247 (A), CagA1–885 (B), and CagA885–1054 (C) are shown. D, circular dichroism spectra of CagF (orange), CagA (brown), and CagA-CagF complex (light green) and the summation of the CagF and CagA spectra (dark green). Isothermal titration calorimetry binding curves of CagFWT titrated against CagA1–409 (E), CagA256–1247 (F), CagA409–885 (G), and CagA256–885 (H) are shown.