A duplicated motif controls assembly of zona pellucida domain proteins
A duplicated motif controls assembly of zona pellucida domain proteins
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DOI：
10.1073/pnas.0401600101
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发表时间：
2004-04-20
影响因子：
11.1
通讯作者：
Wassarman, PM
中科院分区：
文献类型：
--
作者：
Jovine, L;Qi, HY;Wassarman, PM
许多分泌的真核糖蛋白在发育、听力、免疫和癌症中发挥重要作用，它们通过透明带(ZP)结构域聚合成细丝和细胞外基质。ZP结构域蛋白被合成为含有C末端前肽的前体，这些前肽在保守的位置上被切割。然而，这一过程的后果和新生蛋白质组装的机制尚不清楚。通过将突变的DNA结构注入发育中的卵母细胞和哺乳动物细胞转染，我们鉴定了一个保守的复制基序[EHP(外部疏水补丁)/IHP(内部疏水补丁)]，调控小鼠ZP蛋白的组装。虽然ZP3的跨膜结构域(TMD)可以被一个不相关的胆小蛋白取代，但EHP或IHP的突变并不阻碍全长ZP3的分泌，但完全取消了它的组装。因为在TMD之前被截断的突变体没有被处理，我们得出结论，哺乳动物ZP蛋白保守的TMD不参与特定的相互作用，但对C末端的处理是必不可少的。ZP前体的切割导致EHP的丢失，从而激活分泌的多肽在ZP结构域内利用IHP进行组装。综上所述，这些发现提示了ZP结构域蛋白组装的一般机制。
Many secreted eukaryotic glycoproteins that play fundamental roles in development, hearing, immunity, and cancer polymerize into filaments and extracellular matrices through zona pellucida (ZP) domains. ZP domain proteins are synthesized as precursors containing C-terminal propeptides that are cleaved at conserved sites. However, the consequences of this processing and the mechanism by which nascent proteins assemble are unclear. By microinjection of mutated DNA constructs into growing oocytes and mammalian cell transfection, we have identified a conserved duplicated motif [EHP (external hydrophobic patch)/IHP (internal hydrophobic patch)] regulating the assembly of mouse ZP proteins. Whereas the transmembrane domain (TMD) of ZP3 can be functionally replaced by an unrelated TIMID, mutations in either EHP or IHP do not hinder secretion of full-length ZP3 but completely abolish its assembly. Because mutants truncated before the TMD are not processed, we conclude that the conserved TMD of mammalian ZP proteins does not engage them in specific interactions but is essential for C-terminal processing. Cleavage of ZP precursors results in loss of the EHP, thereby activating secreted polypeptides to assemble by using the IHP within the ZP domain. Taken together, these findings suggest a general mechanism for assembly of ZP domain proteins.