Model of how ankyrin chain compression influences the mechanics at the NOMPC channel domain. In stage 1 of compression (upper box), before helix–helix contact at 15 Å, the channel mechanics can be decomposed into three motions: (1) compression of the helical bundle along the z axis, (2) rigid body CCW rotation of the entire channel domain in the membrane, and (3) CW torques applied to each linker/TRP domain that would cause the TRP domain to rotate CW opening the pore as suggested for TRPV1 (Cao et al., 2013). In stage 2, once the compression exceeds 15 Å, the mechanics of the channel differ depending on the type of interactions that occur after helix–helix contact. Both models continue to experience a compression of the helical bundle, but in the frictionless contact model, the channel domain switches directions, causing a rigid body rotation in the CW direction and a change in the torque applied to each TRP domain (right lower box). This later torque change would cause the linker helices and TRP domain to move back to its original position, potentially closing the channel. The rough contact model always experiences a CW torque on the linker helices/TRP domain that continues to move it into the putative open configuration, but the channel domain undergoes minor, rigid body rotations back and forth in the membrane, ultimately continuing the CCW rotation experienced early on (left lower box). Another important difference with the rough contact model is that the chains lock up dramatically increasing the stiffness to vertical displacements. In all figures, the initial configurations are gray and/or black, and the final configurations are cyan. The view of the channel domains is from the cytoplasm.