哺乳動物受精過程（遵循兩個物種都必需有特異性,、且一個精子對一個卵子的準(zhǔn)則）的第一步是,，包裹卵子的膜（稱之為卵膜）中的外殼蛋白與精子之間的識別。小鼠卵膜蛋白ZP3是精子的主要受體,，而且其最保守區(qū)域(ZP-N)也見于具有一系列生物功能的數(shù)百種不同細(xì)胞外蛋白中?，F(xiàn)在,，ZP3的ZP-N區(qū)域的晶體結(jié)構(gòu)已被確定。ZP-N采取一個免疫球蛋白一樣的折疊方式,，但與其他免疫球蛋白區(qū)域幾乎沒有相似之處,，這使其成為這一超級家族的一個新亞型。除了使我們能夠有機(jī)會以原子分辨率一瞥哺乳動物受精過程之外,，ZP3 ZP-N的結(jié)構(gòu)對于生殖醫(yī)學(xué)研究,、對于諸如非癥候耳聾或腎臟和血管疾病等（這些疾病中也涉及含ZP-N的蛋白）的研究也有參考意義。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 456, 653-657 (4 December 2008) | doi:10.1038/nature07599
Crystal structure of the ZP-N domain of ZP3 reveals the core fold of animal egg coats
Magnus Monné1,2, Ling Han1,2, Thomas Schwend1, Sofia Burendahl1 & Luca Jovine1
1 Karolinska Institutet, Department of Biosciences and Nutrition, H?lsov?gen 7, SE-141 57 Huddinge, Sweden
2 These authors contributed equally to this work.
Species-specific recognition between the egg extracellular matrix (zona pellucida) and sperm is the first, crucial step of mammalian fertilization1. Zona pellucida filament components ZP3 and ZP2 act as sperm receptors, and mice lacking either of the corresponding genes produce oocytes without a zona pellucida and are completely infertile2. Like their counterparts in the vitelline envelope of non-mammalian eggs and many other secreted eukaryotic proteins, zona pellucida subunits polymerize using a 'zona pellucida (ZP) domain' module3, 4, 5, whose conserved amino-terminal part (ZP-N) was suggested to constitute a domain of its own6. No atomic structure has been reported for ZP domain proteins, and there is no structural information on any conserved vertebrate protein that is essential for fertilization and directly involved in egg–sperm binding. Here we describe the 2.3 ångström (Å) resolution structure of the ZP-N fragment of mouse primary sperm receptor ZP3. The ZP-N fold defines a new immunoglobulin superfamily subtype with a β-sheet extension characterized by an E' strand and an invariant tyrosine residue implicated in polymerization. The structure strongly supports the presence of ZP-N repeats within the N-terminal region of ZP2 and other vertebrate zona pellucida/vitelline envelope proteins, with implications for overall egg coat architecture, the post-fertilization block to polyspermy and speciation. Moreover, it provides an important framework for understanding human diseases caused by mutations in ZP domain proteins and developing new methods of non-hormonal contraception.
