Fig. 6.

Intermembrane lipid transfer and membrane fusion assays. A: Upper panel depicts an illustration of a GM2AP-mediated intermembrane transfer process. Lower panel demonstrates that the membrane-spanning NBD-MSPE is almost resistant to extraction by GM2AP, whereas both NBD-PE and Rh-PE are not and are transferred from donor to acceptor liposomes with concomitant dequench of fluorescence. For NBD-PE, the quencher was TAMRA-MSPE, and for Rh-PE, the quencher was ATTO-MSPE. B: Upper panel shows an illustration of a fusion process of donor and acceptor liposomes. Lower panel demonstrates that a recombinant protein with a His-tag (i.e., Sap C x His₆) causes immediate fusion of the vesicles. In the absence of protein, no fusion occurs. A 100% dequench is defined by the fluorescence measured in the absence of quencher. A, acceptor liposome; D, donor liposome. SEM was in the range of 3–5% (n = 3).