Raiborg Camilla, Rusten Tor Erik, Stenmark Harald
Department of Biochemistry, Institute for Cancer Research, the Norwegian Radium Hospital, Montebello, N-0310, Oslo, Norway.
Curr Opin Cell Biol. 2003 Aug;15(4):446-55. doi: 10.1016/s0955-0674(03)00080-2.
Multivesicular endosomes are important as compartments for receptor downregulation and as intermediates in the formation of secretory lysosomes. Work during the past year has shed light on the molecular mechanisms of protein sorting into multivesicular endosomes and yielded information about the machinery involved in multivesicular endosome formation. Monoubiquitination functions as a signal for sorting transmembrane proteins into intraluminal vesicles of multivesicular endosomes and subsequent delivery to lysosomes. A molecular machinery that contains the ubiquitin-binding protein Hrs/Vps27 appears to be central in this sorting process. Three conserved multisubunit complexes, ESCRT-I, -II and -III, are essential for both sorting and multivesicular endosomes formation. Enveloped RNA viruses such as HIV can redirect these complexes from multivesicular endosomes to the plasma membrane to facilitate viral budding.
多囊泡内体作为受体下调的区室以及分泌性溶酶体形成的中间体具有重要意义。过去一年的研究揭示了蛋白质分选进入多囊泡内体的分子机制，并提供了有关多囊泡内体形成所涉及机制的信息。单泛素化作为一种信号，用于将跨膜蛋白分选到多囊泡内体的腔内小泡中，并随后递送至溶酶体。一种包含泛素结合蛋白Hrs/Vps27的分子机制似乎在这一分选过程中起核心作用。三种保守的多亚基复合物，即ESCRT-I、-II和-III，对于分选和多囊泡内体形成均至关重要。诸如HIV等包膜RNA病毒可将这些复合物从多囊泡内体重定向至质膜，以促进病毒出芽。
