Sabharanjak Shefali, Sharma Pranav, Parton Robert G, Mayor Satyajit
National Centre for Biological Sciences, UAS-GKVK Campus, Bellary Road, 560 065, Bangalore, India.
Dev Cell. 2002 Apr;2(4):411-23. doi: 10.1016/s1534-5807(02)00145-4.
Endocytosis of cell-surface proteins via specific pathways is critical for their function. We show that multiple glycosylphosphatidylinositol-anchored proteins (GPI-APs) are endocytosed to the recycling endosomal compartment but not to the Golgi via a nonclathrin, noncaveolae mediated pathway. GPI anchoring is a positive signal for internalization into rab5-independent tubular-vesicular endosomes also responsible for a major fraction of fluid-phase uptake; molecules merely lacking cytoplasmic extensions are not included. Unlike the internalization of detergent-resistant membrane (DRM)-associated interleukin 2 receptor, endocytosis of DRM-associated GPI-APs is unaffected by inhibition of RhoA or dynamin 2 activity. Inhibition of Rho family GTPase cdc42, but not Rac1, reduces fluid-phase uptake and redistributes GPI-APs to the clathrin-mediated pathway. These results describe a distinct constitutive pinocytic pathway, specifically regulated by cdc42.
通过特定途径对细胞表面蛋白进行内吞作用对其功能至关重要。我们发现，多种糖基磷脂酰肌醇锚定蛋白（GPI-APs）通过非网格蛋白、非小窝介导的途径被内吞至回收型内体区室，但不会被内吞至高尔基体。GPI锚定是内化进入不依赖rab5的管状囊泡内体的一个正向信号，这些内体也负责大部分液相摄取；仅仅缺乏细胞质延伸的分子不包括在内。与抗去污剂膜（DRM）相关的白细胞介素2受体的内化不同，DRM相关的GPI-APs的内吞作用不受RhoA或发动蛋白2活性抑制的影响。Rho家族GTP酶cdc42的抑制而非Rac1的抑制会减少液相摄取并将GPI-APs重新分布至网格蛋白介导的途径。这些结果描述了一种由cdc42特异性调控的独特组成型胞饮途径。
