Phospholipid demixing and the birth of a lipid droplet

摘要: The biogenesis of lipid droplets (LD) in the yeast Saccharomyces cerevisiae was theoretically investigated on basis a biophysical model. In accordance with prevailing model LD formation, we assumed that neutral lipids oil-out between membrane leaflets endoplasmic reticulum (ER), resulting bud-off when critical size is reached. Mathematically, were modeled as spherical protuberances an otherwise planar ER membrane. We estimated local phospholipid composition, and calculated change elastic free energy caused by nascent LD. Based this calculation, found gradual demixing leaflet goes along increase surface curvature at site formation. During demixing, monolayer able to gain during growth, which suggested formation curved interfaces supported or even driven demixing. addition, show thermodynamically necessary cannot otherwise. case our predicts diameter about 12 nm. This far below experimentally determined typical Thus, concluded if standard valid, two step process. Small are produced from ER, subsequently ripe within cytosol through series fusions.