| Popis: |
Several mechanisms have been proposed by which lipids are translocated between membranes of eukaryotic cells: (i) transport of lipid monomers with or without the aid of soluble carrier proteins; (ii) vesicle flux; and (iii) migration of lipids between donor and acceptor through membrane contact (for a recent review see Trotter and Voelker, 1994). The aim of the present study was to characterize the transport of aminoglycerophospholipids between the endoplasmic reticulum and the mitochondria of the yeast, Saccharomyces cerevisiae. This process is important because synthesis of phosphatidylethanolamine catalyzed by the mitochondrial phosphatidylserine decarboxylase, Psdlp (Trotter et al., 1993), requires import into mitochondria of phosphatidylserine formed by phosphatidylserine synthase in the endoplasmic reticulum (Zinser et al., 1991). In intact mammalian cells the rate of phosphatidylserine transport from microsomes to mitochondria is reduced by the energy blockers azide and fluoride (Voelker, 1988) and enhanced by ATP in permeabilized cells (Voelker, 1989b; 1990; 1993). Interorganelle translocation of phosphatidylserine was shown to be independent of cytosolic factors in permeabilized mammalian cells (Voelker, 1989b) and in a cell free system (Voelker, 1989a). |
