Sorting of mannose 6-phosphate receptors and lysosomal membrane proteins in endocytic vesicles.
Sorting of mannose 6-phosphate receptors and lysosomal membrane proteins in endocytic vesicles.
复制标题
内吞囊泡中的甘露糖6-磷酸受体和溶酶体膜蛋白的分选。
DOI：
10.1083/jcb.107.6.2491
复制
发表时间：
1988-12
影响因子：
7.8
通讯作者：
Mellman, I
中科院分区：
文献类型：
--
作者：
Geuze, H J;Stoorvogel, W;Strous, G J;Slot, J W;Bleekemolen, J E;Mellman, I
研究了非阳离子依赖性甘露糖6-磷酸受体（MPR）和120-kD溶酶体膜糖蛋白（lgp 120）在大鼠肝癌细胞内的分布。使用定量免疫金细胞化学，我们发现10%的细胞的MPR位于细胞表面。相反，lgp 120在质膜上检测不到。在细胞内，MPR主要发生在反式高尔基体网（TGR）和内体。另一方面，lgp 120局限于内体和溶酶体。MPR存在于内体小管和空泡中，而lgp 120仅限于内体空泡。在与内吞示踪剂阳离子化铁蛋白孵育5-60分钟的细胞中，可以辨别出四类内吞空泡，即，空泡命名为MPR+/lgp 120-、MPR+/lgp 120+、MPR-/lgp 120+，空泡未免疫标记为MPR和lgp 120。示踪剂首先到达MPR+/lgp 120-，然后到达MPR+/lgp 120+，最后到达MPR-/lgp 120+空泡，这些空泡被认为代表溶酶体。为了更详细地研究MPR-和/或lgp 120-含有池中出现内吞示踪剂的动力学，允许细胞内吞辣根过氧化物酶（HRP）5-90 min。由于用3 '3-二氨基联苯胺处理细胞匀浆，因此在Western印迹上MPR和lgp 120抗原性的可检测性降低，随后及时进行。我们发现，HRP到达MPR的整个访问池几乎立即内化后的示踪剂，而HRP最大限度地访问lgp 120所需的时间延长。综合数据表明，MPR+/lgp 120+空泡是内吞空泡，介于MPR+/lgp 120-内体和MPR-/lgp 120+溶酶体之间，代表MPR从lgp 120中分选到溶酶体的位点。我们建议，MPR是从lgp 120的选择性横向分布的受体进入本室的小管，导致在液泡中的lgp 120的保留和lgp 120的净运输到溶酶体。
The intracellular distributions of the cation-independent mannose 6- phosphate receptor (MPR) and a 120-kD lysosomal membrane glycoprotein (lgp120) were studied in rat hepatoma cells. Using quantitative immunogold cytochemistry we found 10% of the cell's MPR located at the cell surface. In contrast, lgp120 was not detectable at the plasma membrane. Intracellularly, MPR mainly occurred in the trans-Golgi reticulum (TGR) and endosomes. lgp120, on the other hand, was confined to endosomes and lysosomes. MPR was present in both endosomal tubules and vacuoles, whereas lgp120 was confined to the endosomal vacuoles. In cells incubated for 5-60 min with the endocytic tracer cationized ferritin, four categories of endocytic vacuoles could be discerned, i.e., vacuoles designated MPR+/lgp120-, MPR+/lgp120+, MPR-/lgp120+, and vacuoles nonimmunolabeled for MPR and lgp120. Tracer first reached MPR+/lgp120-, then MPR+/lgp120+, and finally MPR-/lgp120+ vacuoles, which are assumed to represent lysosomes. To study the kinetics of appearance of endocytic tracers in MPR-and/or lgp120-containing pools in greater detail, cells were allowed to endocytose horse-radish peroxidase (HRP) for 5-90 min. The reduction in detectability of MPR and lgp120 antigenicity on Western blots, due to treatment of cell homogenates with 3'3-diaminobenzidine, was followed in time. We found that HRP reached the entire accessible pool of MPR almost immediately after internalization of the tracer, while prolonged periods of time were required for HRP to maximally access lgp120. The combined data suggest that MPR+/lgp120+ vacuoles are endocytic vacuoles, intermediate between MPR+/lgp120-endosomes and MPR-/lgp120+ lysosomes, and represent the site where MPR is sorted from lgp120 destined for lysosomes. We propose that MPR is sorted from lgp120 by selective lateral distribution of the receptor into the tubules of this compartment, resulting in the retention of lgp120 in the vacuoles and the net transport of lgp120 to lysosomes.