Piper Robert C, Luzio J Paul
Department of Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA.
Curr Opin Cell Biol. 2007 Aug;19(4):459-65. doi: 10.1016/j.ceb.2007.07.002. Epub 2007 Aug 3.
The pathways that deliver newly synthesized proteins that reside in lysosomes are well understood on comparison with our knowledge of how integral membrane proteins are sorted and delivered to the lysosome for degradation. Many membrane proteins are sorted to lysosomes following ubiquitination, which provides a sorting signal that can operate for sorting at the TGN (trans-Golgi network), at the plasma membrane or at the endosome for delivery into lumenal vesicles. Candidate multicomponent machines that can potentially move ubiquitinated integral membrane cargo proteins have been identified, but much work is still required to ascertain which of these candidates directly recognize ubiquitinated cargo and what they do with cargo after recognition. In the case of the machinery required for sorting into the lumenal vesicles of endosomes, other functions have also been determined including a link between sorting and movement of endosomes along microtubules.
与我们对整合膜蛋白如何分选并运输到溶酶体进行降解的了解相比,将驻留在溶酶体中的新合成蛋白质运输到溶酶体的途径已得到充分了解。许多膜蛋白在泛素化后被分选到溶酶体,泛素化提供了一个分选信号,该信号可在反式高尔基体网络(TGN)、质膜或内体处进行分选,以便运输到腔内小泡。已经鉴定出可能运输泛素化整合膜货物蛋白的候选多组分机制,但仍需要大量工作来确定这些候选机制中哪些直接识别泛素化货物,以及识别后它们如何处理货物。就分选到内体腔内小泡所需的机制而言,还确定了其他功能,包括分选与内体沿微管移动之间的联系。