Cell Biological Analysis of Lipidic Supramolecular Structure

(1)我们发现脂化ApoB从ER腔移位到脂滴表面进行蛋白酶体降解，并且UBXD 8和Derlin-1在该机制中起关键作用。Derlin-1参与位错步骤，而UBXD 8在位错后起作用。这一结果阐明了ApoB在脂滴表面降解的分子机制。(2)我们证明了纳米级分布的磷脂酰肌醇4，5二磷酸[PI（4，5）P2]的快速冷冻，冷冻断裂复制标记方法。结果表明：在体外培养的成纤维细胞中，PI（4，5）P2主要集中在小窝口和被膜小凹处，表现出与扁平未分化膜区不同的行为;在体内培养的大鼠胰腺上皮细胞中，PI（4，5）P2主要集中在差距连接处。

(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.