Cell Biological Analysis of Lipidic Supramolecular Structure

(1)我们发现脂化ApoB从内质网腔脱位到脂滴表面进行蛋白酶体降解，UBXD8和Derlin-1参与了该机制的关键作用。Derlin-1参与位错步骤，而UBXD8在位错之后起作用。结果阐明了脂滴表面ApoB降解过程的分子机制。(2)我们通过速冻、冻裂复制标记的方法证明了磷脂酰肌醇4,5 -二磷酸[PI(4,5) P2]的纳米级分布。结果表明：在培养成纤维细胞中，PI(4,5) P2集中在小泡孔和包被凹处，表现出与扁平未分化膜区不同的行为；在大鼠胰腺上皮细胞中，体内发现PI(4,5) P2密集分布于间隙连接处。

(1) We found that lipidated ApoB is dislocated from the ER lumen to the lipid droplet surface for proteasomal degradation and that UBXD8 and Derlin-1 are critically involved in the mechanism. Derlin-1 is engaged in the dislocation step, whereas UBXD8 functions after the dislocation. The result elucidated the molecular mechanism of ApoB degradation process that occurs on the lipid droplet surface.(2) We demonstrated the nanoscale distribution of phosphatidylinositol 4, 5bisphosphate[PI(4, 5) P2] by the quick-freezing, freeze-fracture replica labeling method. The following findings were obtained : in cultured fibroblasts, PI(4, 5) P2 is concentrated at the orifice of caveolae and coated pits and shows different behaviors from that in the flat undifferentiated membrane region ; in rat pancreatic epithelial cells in vivo PI(4, 5) P2 was found densely distributed in the gap junction.