Fig. 3.

Cavities inside tetrameric and pentameric coiled-coil channels. Extraordinary features of COMPcc (A) and RHCC (B) are large cavities along the aliphatic channel core. These cavities (highlighted as yellow van der Waals spheres) can function as storage spaces for a great variety of different cargo systems with large biomedical importance. The volumes of individual cavities are shown in cubic Angstroms (ų). Salt bridges surrounding individual cavities in RHCC are highlighted in red (acidic resdiues) and blue (basic residues). The Gln⁵⁴ ring in COMPcc is drawn in colour atom type. Remarkably, both channels allow for different shapes of interior spaces. Whereas RHCC cavities are regularly-arranged separated balls, both cavities in COMPcc are elongated and separated by the Gln⁵⁴ ring in the d-position.