|
  
- 积分
- 0
- 威望
- 0
- 包包
- 3465
|
Nichols/Macmillan! @8 b& n; z+ F2 \1 ? w1 x. L
+ ?; f; w8 X( J0 Q1 Q5 mClathrin-independent endocytosis is revealing itself at last. Intermediary organelles in this pathway have been difficult to identify, due in part to a dearth of markers and, until recently, difficulties in blocking the clathrin-dependent process. But now, Benjamin Nichols (MRC Laboratory of Molecular Biology, Cambridge, UK) has identified a set of endosomes that are uniquely involved in clathrin-independent trafficking.Nichols' results demonstrate that vesicles containing caveolin-1 define a set of early endosomes that are distinct from those that form from clathrin-coated pits. Proteins that were endocytosed independently of clathrin, including GPI-anchored proteins and the cholera toxin B subunit, were found within the caveolin-1–positive endosomes. Even in the absence of clathrin-mediated endocytosis, these proteins were delivered from the plasma membrane to the Golgi.1 j8 Y3 \6 @& u* |- ]. q
( k' @/ c! j- |" d) {
Although caveolin-1 provides a useful marker for the pathway, the protein was not important for endocytosis. Nichols found that caveolin-1 was sorted away from Golgi-bound vesicles, and diminished caveolin-1 levels did not inhibit clathrin-independent endocytosis. Caveolin-1–containing endosomes have previously been shown to transport SV40 virus to the ER. Nichols believes these may be the same organelles, although this is not yet proven./ E$ @/ H$ d. e! H
% T/ p8 f( J4 m2 \8 ~1 H
The function of the clathrin-independent pathway will be better understood when specific inhibitors can be identified. For now, Nichols hypothesizes that clathrin-independent endocytosis is important for delivery of certain plasma membrane lipids to the trans face of the Golgi, the site of lipid raft formation and Golgi cargo sorting.# y& l0 a0 e/ D( Q$ O" o6 V
1 t% A. |( E s tReference:; b, K& X) C. `3 o' M
( [( o& s) b. f& ?$ ~5 ? INichols, B. 2002. Nat. Cell Biol. 10.1038/ncb787.(Caveolin-1 (green) endosomes carry cargo) |
|
发表于 2009-3-6 00:13
发表于 2015-6-10 20:54
