FIG. 2.

Established or predicted topologies for channel proteins (A), carrier proteins (B), and proteins of unknown transport mode (C). The proteins included in A are the channel proteins of TC category 1.A, while the carriers represented in B are the families of TC category 2.1A. Because most primary carriers of categories 3 consist of heterooligomers, many of very complex structure, these were not included in the analyses depicted.