Schulze-Garg C, Böker C, Nadimpalli S K, von Figura K, Hille-Rehfeld A
Universität Göttingen, Federal Republic of Germany.
J Cell Biol. 1993 Aug;122(3):541-51. doi: 10.1083/jcb.122.3.541.
Recycling of 46,000 M(r) mannose 6-phosphate receptor (MPR 46) was investigated by microinjection of Fab fragments against small epitopes within the cytoplasmic domain of the receptor. Fab fragments against the peptide 43-47 (Ala-Tyr-Arg-Gly-Val) efficiently blocked return of MPR 46 to the TGN. Antibody-induced redistribution resulted in accumulation of MPR 46 within an endosomal compartment, from which it recycled to the plasma membrane. Rab5 and rab7, markers for early and late endosomes, respectively, were not detectable in the compartment of redistributed MPR 46, suggesting that it represents a specialized endosomal subcompartment. The bulk of redistributed MPR 46 did not colocalize with endocytosed fluid-phase marker, suggesting that it accumulates at a site where MPR 46 has been segregated from endocytosed material, which is destined for transport to lysosomes. Peptide 43-47 contains a tyrosine (residue 44) which has been shown earlier to be part of an internalization signal for MPR 46 (Johnson, K. F., W. Chan, and S. Kornfeld. 1990. Proc. Natl. Acad. Sci. USA. 87:10010-10014). The role of tyrosine residue 44 as part of a putative multifunctional sorting signal is discussed.
通过显微注射针对受体胞质结构域内小表位的Fab片段，研究了46,000 M(r) 甘露糖6-磷酸受体（MPR 46）的再循环。针对肽段43 - 47（丙氨酸-酪氨酸-精氨酸-甘氨酸-缬氨酸）的Fab片段有效地阻断了MPR 46返回反式高尔基体网络（TGN）。抗体诱导的再分布导致MPR 46在内体区室中积累，然后它从该区室再循环至质膜。分别作为早期和晚期内体标志物的Rab5和rab7，在再分布的MPR 46区室中未检测到，这表明它代表一个特殊的内体亚区室。大部分再分布的MPR 46不与内吞的液相标志物共定位，这表明它在MPR 46与内吞物质分离的位点积累，内吞物质 destined for transport to lysosomes。肽段43 - 47含有一个酪氨酸（第44位残基），先前已证明它是MPR 46内化信号的一部分（约翰逊，K.F.，W. 陈，和S. 科恩菲尔德。1990. 美国国家科学院院刊。87:10010 - 10014）。讨论了酪氨酸残基44作为假定的多功能分选信号一部分的作用。 （注：原文中“which is destined for transport to lysosomes”前面“endocytosed material”后可能有缺失信息；“destined for”直译为“注定用于”，这里结合语境意译为“运往”更合适，但整体按要求未做过多调整）
