ABALONE EGG COAT PROTEINS

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。含有透明带（ZP）结构域的蛋白质是脊椎动物卵皮的重要组成部分。尽管对无脊椎海洋腹足鲍鱼（haaliotis spp.）的卵皮的特征不太清楚，但也已知含有ZP结构域蛋白，这提高了后生动物卵皮结构的共同分子基础的可能性。脊椎动物和无脊椎动物类群的蛋壳蛋白都是在正选择下进化的。在鲍鱼系统中，研究最广泛的是适应性分化的卵皮和精子蛋白之间的共同进化，这可能有助于生殖隔离的快速发展。因此，确定蛋壳蛋白的进化模式对于理解这些基因在物种形成过程中可能发挥的作用是重要的。本研究的目的是表征鲍鱼卵的卵皮（卵黄包膜，VE）的组成蛋白，并为鲍鱼进化过程中选择如何作用于VE蛋白提供初步证据。我们使用蛋白质组学方法将纯化的VE蛋白肽的串联质谱与鲍鱼卵巢EST序列进行匹配，并鉴定出10个新的ZP结构域蛋白中的9个是VE的组成部分。密码子进化的最大似然模型表明，正向选择在这些基因中的6个氨基酸子集中起作用。这项工作进一步证明了ZP蛋白作为卵皮成分的重要性，以及正选择在这些生殖蛋白多样化中的突出作用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Proteins harboring a zona pellucida (ZP) domain are prominent components of vertebrate egg coats. Although less well characterized, the egg coat of the invertebrate marine gastropod abalone (Haliotis spp.) is also known to contain a ZP domain protein, raising the possibility of a common molecular basis of metazoan egg coat structures. Egg coat proteins from vertebrate as well as invertebrate taxa have been shown to evolve under positive selection. Studied most extensively in the abalone system, coevolution between adaptively diverging egg coat and sperm proteins may contribute to the rapid development of reproductive isolation. Thus identifying the pattern of evolution among egg coat proteins is important in understanding the role these genes may play in the speciation process. The purpose of the present study is to characterize the constituent proteins of the egg coat (vitelline envelope, VE) of abalone eggs, and to provide preliminary evidence regarding how selection has acted on VE proteins during abalone evolution. We use a proteomic approach to match tandem mass spectra of peptides from purified VE proteins with abalone ovary EST sequences, and identify 9 of 10 novel ZP domain proteins as components of the VE. Maximum likelihood models of codon evolution suggest positive selection has acted among a subset of amino acids for 6 of these genes. This work provides further evidence of the prominence of ZP proteins as constituents of the egg coat, as well as the prominent role of positive selection in diversification of these reproductive proteins.