Figure 1

Schematic diagram of TM protein topology. The number of TM helices, the lengths of the N- and C-terminal domains, and the sizes of the interhelical loops or domains vary. Some TM proteins are located predominantly within the membrane (D), but others have more extensive N- or C-termini and/or cytoplasmic or periplasmic loops (A, B, C) that can form independently folding globular domains.