Dissecting the Molecular Mechanisms of Polarized Membrane Traffic: Reconstitution of Three Transport Steps in Epithelial Cells Using Streptolysin-O Permeabilization

The interorganelle transport of proteins is known to be mediated by carrier vesicles that bud from the donor compartment and transfer their content to the acceptor compartment in a series of highly regulated reactions. To gain access to the underlying molecular mechanisms, it is necessary to develop systems that allow the reconstitution of these events in vitro. Such assays have been established during the past 10 years for various eukaryotic cell types, ranging from yeast to mammalian cells (Balch et al. 1984; Baker et al. 1988; Ruohola et al. 1988; Woodman and Warren 1989), and have proven their power by providing insight into the reactions at the molecular level. A key element of these assays is that they permit a high degree of experimental manipulation combined with precise quantitative measurements. This is achieved in two ways: (1) assays where the donor and acceptor compartments are isolated from cell homogenates and...