Chamberlin M E, Dean J
Laboratory of Cellular and Developmental Biology, National Institute of Arthritis, Diabetes, and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.
Proc Natl Acad Sci U S A. 1990 Aug;87(16):6014-8. doi: 10.1073/pnas.87.16.6014.
The human zona pellucida, composed of three glycoproteins (ZP1, ZP2, and ZP3), forms an extracellular matrix that surrounds ovulated eggs and mediates species-specific fertilization. The genes that code for at least two of the zona proteins (ZP2 and ZP3) cross-hybridize with other mammalian DNA. The recently characterized mouse sperm receptor gene (Zp-3) was used to isolate its human homolog. The human homolog spans approximately 18.3 kilobase pairs (kbp) (compared to 8.6 kbp for the mouse gene) and contains eight exons, the sizes of which are strictly conserved between the two species. Four short (8-15 bp) sequences within the first 250 bp of the 5' flanking region in the human Zp-3 homolog are also present upstream of mouse Zp-3. These elements may modulate oocyte-specific gene expression. By using the polymerase chain reaction, a full-length cDNA of human ZP3 was isolated from human ovarian poly(A)+ RNA and used to deduce the structure of human ZP3 mRNA. Certain features of the human and mouse ZP3 transcripts are conserved. Both have unusually short 5' and 3' untranslated regions, both contain a single open reading frame that is 74% identical, and both code for 424 amino acid polypeptides that are 67% the same. The similarity between the two proteins may define domains that are important in maintaining the structural integrity of the zona pellucida, while the differences may play a role in mediating the species-specific events of mammalian fertilization.
人类透明带由三种糖蛋白（ZP1、ZP2和ZP3）组成，形成围绕排卵卵子的细胞外基质，并介导物种特异性受精。编码至少两种透明带蛋白（ZP2和ZP3）的基因与其他哺乳动物的DNA发生交叉杂交。最近鉴定的小鼠精子受体基因（Zp-3）被用于分离其人类同源物。人类同源物跨度约为18.3千碱基对（kbp）（小鼠基因则为8.6 kbp），包含八个外显子，其大小在两个物种之间严格保守。人类Zp-3同源物5'侧翼区前250 bp内的四个短序列（8 - 15 bp）也存在于小鼠Zp-3的上游。这些元件可能调节卵母细胞特异性基因表达。通过聚合酶链反应，从人卵巢poly(A)+ RNA中分离出人类ZP3的全长cDNA，并用于推导人类ZP3 mRNA的结构。人类和小鼠ZP3转录本的某些特征是保守的。两者都有异常短的5'和3'非翻译区，都包含一个单一的开放阅读框且其一致性为74%，都编码424个氨基酸的多肽且两者相同度为67%。这两种蛋白质之间的相似性可能定义了在维持透明带结构完整性方面重要的结构域差异，而这些差异可能在介导哺乳动物受精的物种特异性事件中发挥作用。
