Figure 2

Schematic representation of the topology of the gp41-CT. A. Conventional model, in which gp41 spans the membrane once and the membrane-spanning domain (MSD) is an α-helix (boxed). B. Alternative model in which the gp41-CT crosses the membrane three times via antiparallel β-sheets (arrows) and the KE is exposed extracellularly. Adapted from Steckbeck et al. PlosOne 2010 [71]. C. LLP-2 is a membrane-traversing peptide or a “carrier” peptide and may interact with the HR1-HR2 6-helix bundle at the moment of fusion. In this conformation, the KE would also traverse the plasma membrane. Adapted from Lu et al. J Biol Chem 2008 [60].