Two lysosomal membrane proteins, LGP85 and LGP107, are delivered to late endosomes/lysosomes through different intracellular routes after exiting from the trans-Golgi network

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• 作者：Niwa ; Kazuo ; Tanaka ; Rie ; Murase ; Hiroshi ; Ishikawa ; Toyoko ; Fujita ; Hideaki ; Himeno ; Masaru ; et. al.
• 关键词：Lysosomal membrane protein ; LGP85 (LIMP II) ; Intracellular transport ; Early endosome
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2003
• 出版时间：February 21, 2003
• 年：2003
• 卷：301
• 期：4
• 页码：833-840
• 全文大小：285 K

文摘

Lysosomal membrane proteins are delivered from their synthesis site, the endoplasmic reticulum (ER) to late endosomes/lysosomes through the Golgi complex. It has been proposed that after leaving the Golgi they are transported either directly or indirectly (via the cell surface) to late endosomes/lysosomes. In the present study, we examined the transport routes taken by two structurally different lysosomal membrane proteins, LGP85 and LGP107, in rat 3Y1-B cells. Here we show that newly synthesized LGP85 and LGP107 are delivered to late endosomes/lysosomes via a direct route without passing through the cell surface. Interestingly, although LGP107 is delivered from the Golgi to early endosomes containing internalized horseradish peroxidase-conjugated transferrin (HRP-Tfn) en route to lysosomes, LGP85 does not pass through the HRP-Tfn-positive early endosomes. These results suggest, therefore, that LGP85 and LGP107 are sorted into distinct transport vesicles at the post-Golgi, presumably the trans-Golgi network (TGN), after which LGP85 is delivered directly to late endosomes/lysosomes, but significant fractions of LGP107 are targeted to early endosomes before transport to late endosomes/lysosomes. This study provides the first evidence that after exiting from the Golgi, LGP85 and LGP107 are targeted to late endosomes/lysosomes via a different pathway.