Adipophilin-enriched domains in the ER membrane are sites of lipid droplet biogenesis

摘要: The prevailing hypothesis of lipid droplet biogenesis proposes that neutral lipids accumulate within the bilayer ER membrane from where they are budded off, enclosed by a protein-bearing phospholipid monolayer originating cytoplasmic leaflet membrane. We have used variety methods to investigate nature sites ER-lipid-droplet association in order gain new insights into mechanism formation and growth. three-dimensional perspectives provided freeze-fracture electron microscopy demonstrate unequivocally at close association, is not situated membrane; rather, both membranes lie external follow contour droplet, enclosing it manner akin an egg cup (the ER) holding droplet). Freeze-fracture cytochemistry demonstrates PAT family protein adipophilin concentrated prominent clusters closely apposed envelope. identify these structures as which transferred droplets. These findings call for re-evaluation biogenesis.