Fig. 1. Architecture of the NHE1-CHP1 complex.

a, b Overall structures of the NHE1-CHP1 complex, in the absence and presence of cariporide, respectively. Two subunits of NHE1 are colored in orange and blue, and two CHP1 subunits are colored in magenta. Gray lines represent boundaries of the cell membrane. The black dots depict the centers of mass (COMs) of the E^4th helix of CHP1. The height of the complex and the distance between COMs are indicated. c, d Structure of the NHE1 protomer in the NHE1-CHP1^K/cariporide complex, viewed in the membrane plane and from the extracellular side, respectively. The peptide backbone of NHE1 is colored in a rainbow scheme, with blue and red for the amino and carboxyl termini, respectively. The core and dimerization domains are shown in cartoon and cylinder, respectively. The CHP1 molecule is displayed as a transparent pink surface model. 2-fold symmetry axis are depicted as a gray stick or black oval. The core domain is highlighted with a gray oval.