ZP2 and ZP3 traffic independently within oocytes prior to assembly into the extracellular zona pellucida
ZP2 and ZP3 traffic independently within oocytes prior to assembly into the extracellular zona pellucida
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DOI：
10.1128/mcb.00904-06
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发表时间：
2006-11-01
影响因子：
5.3
通讯作者：
Dean, Jurrien
中科院分区：
文献类型：
--
作者：
Hoodbhoy, Tanya;Aviles, Manuel;Dean, Jurrien
细胞外的透明带包围着哺乳动物的卵子，并在受精时介导分类群特异性的精卵识别。在小鼠体内，透明带由三种糖蛋白组成，但ZP2和ZP3的存在足以形成一个生物功能结构。每一种透明带糖蛋白都是在生长的卵母细胞中合成的，并通过内膜系统运输到细胞表面，在那里它从跨膜区释放出来，并组装成不溶的透明带基质。ZP2和ZP3共定位于内质网和由多泡聚集体(MVA)组成的1-5微米的高尔基体后结构中，但免疫共沉淀试验不能检测到物理相互作用。此外，ZP2在缺乏ZP3或ZP3发生突变以阻止整合到透明带基质中的情况下，正常地在发育中的卵母细胞中运输，补充了早期关于ZP3在ZP2基因缺失小鼠中独立分泌的研究。N糖基化与正确的蛋白质折叠和分泌蛋白质的细胞内运输有关。虽然ZP3含有5个N-糖链，但增强型绿色荧光蛋白标记的ZP3在WA中存在N个糖基化位点，并被整合到转基因小鼠的透明带基质中。因此，ZP2的分泌似乎不受缺乏N-糖链的ZP3的影响。综上所述，这些观察表明，ZP2和ZP3在装配到透明带之前独立地通过卵母细胞运输。
The extracellular zona pellucida surrounds mammalian eggs and mediates taxon-specific sperm-egg recognition at fertilization. In mice, the zona pellucida is composed of three glycoproteins, but the presence of ZP2 and ZP3 is sufficient to form a biologically functional structure. Each zona pellucida glycoprotein is synthesized in growing oocytes and traffics through the endomembrane system to the cell surface, where it is released from a transmembrane domain and assembled into the insoluble zona pellucida matrix. ZP2 and ZP3 colocalize in the endoplasmic reticulum and in 1- to 5-mu m post-Golgi structures comprising multivesicular aggregates (MVA), but a coimmunoprecipitation assay does not detect physical interactions. In addition, ZP2 traffics normally in growing oocytes in the absence of ZP3 or if ZP3 has been mutated to prevent incorporation into the zona pellucida matrix, complementing earlier studies indicating the independence of ZP3 secretion in Zp2 null mice. N glycosylation has been implicated in correct protein folding and intracellular trafficking of secreted proteins. Although ZP3 contain five N-glycans, enhanced green fluorescent protein-tagged ZP3 lacking N glycosylation sites is present in WA and is incorporated into the zona pellucida matrix of transgenic mice. Thus, ZP2 secretion is seemingly unaffected by ZP3 lacking N-glycans. Taken together, these observations indicate that ZP2 and ZP3 traffic independently through the oocyte prior to assembly into the zona pellucida.