Correctly sorted molecules of a GPI-anchored protein are clustered and immobile when they arrive at the apical surface of MDCK cells.
Correctly sorted molecules of a GPI-anchored protein are clustered and immobile when they arrive at the apical surface of MDCK cells.
复制标题
DOI：
10.1083/jcb.120.2.353
复制
发表时间：
1993-01
期刊：
影响因子：
--
通讯作者：
Edidin M
中科院分区：
文献类型：
--
作者：
Hannan LA;Lisanti MP;Rodriguez-Boulan E;Edidin M
糖基-磷脂酰肌醇（GPI）锚定蛋白被分选到许多上皮细胞类型的顶端表面。为了更好地理解这些蛋白质顶端分离的机制，我们分析了模型GPI锚定蛋白、与人衰变加速因子（gD 1-β）融合的单纯疱疹病毒gD 1的侧向移动性和分子关联（Lisanti，M. P.，I. W.卡拉斯，M. A. Davitz和E.罗德里格斯-布朗1989. 109：2145-2156）。横向扩散的FRAP测量结果表明，新到达的gD 1-β分子的移动的部分远小于长期驻留分子的移动的部分（40对80-90%）。荧光共振能量转移测量表明，新到达的分子聚集，而居民分子没有。新递送的gD 1-β分子在不能分选gD 1-β的突变体伴刀豆球蛋白A抗性MDCK细胞中成簇但不固定。我们的研究结果表明，GPI锚定蛋白在MDCK细胞聚集之前交付到表面。然而，单独的成簇不靶向用于顶端递送的分子。当gD 1-β正确分选时观察到的固定表明簇必须与细胞质的某些组分相关联。
Glycosyl-phosphatidylinositol (GPI)-anchored proteins are sorted to the apical surface of many epithelial cell types. To better understand the mechanism for apical segregation of these proteins, we analyzed the lateral mobility and molecular associations of a model GPI-anchored protein, herpes simplex virus gD1 fused to human decay accelerating factor (gD1-DAF) (Lisanti, M. P., I. W. Caras, M. A. Davitz, and E. Rodriguez-Boulan. 1989. J. Cell Biol. 109:2145-2156) shortly after arrival and after long-term residence at the surface of confluent, polarized MDCK cells. FRAP measurements of lateral diffusion showed that the mobile fraction of newly arrived gD1-DAF molecules was much less than the mobile fraction of long-term resident molecules (40 vs. 80-90%). Fluorescence resonance energy transfer measurements showed that the newly arrived molecules were clustered, while resident molecules were not. Newly delivered gD1-DAF molecules were clustered but not immobilized in mutant, Concanavalin A-resistant MDCK cells that failed to sort gD1-DAF. Our results indicate that GPI-anchored proteins in MDCK cells are clustered before delivery to the surface. However, clustering alone does not target molecules for apical delivery. The immobilization observed when gD1-DAF is correctly sorted suggests that the clusters must associate some component of the cell's cytoplasm.