Odgren P R, Harvie L W, Fey E G
Department of Cell Biology, University of Massachusetts Medical Center, Worcester 01655, USA.
Proteins. 1996 Apr;24(4):467-84. doi: 10.1002/(SICI)1097-0134(199604)24:4<467::AID-PROT6>3.0.CO;2-B.
We examined GenBank sequence files with a heptad repeat analysis program to assess the phylogenetic occurrence of coiled coil proteins, how heptad repeat domains are organized within them, and what structural/functional categories they comprise. Of 102,007 proteins analyzed, 5.95% (6,074) contained coiled coil domains; 1.26% (1,289) contained "extended" (> 75 amino acid) domains. While the frequency of proteins containing coiled coils was surprisingly constant among all biota, extended coiled coil proteins were fourfold more frequent in the animal kingdom and may reflect early events in the divergence of plants and animals. Structure/function categories of extended coils also revealed phylogenetic differences. In pathogens and parasites, many extended coiled coil proteins are external and bind host proteins. In animals, the majority of extended coiled coil proteins were identified as constituents of two protein categories: 1) myosins and motors; or 2) components of the nuclear matrix-intermediate filament scaffold. This scaffold, produced by sequential extraction of epithelial monolayers in situ, contains only 1-2% of the cell mass while accurately retaining morphological features of living epithelium and is greatly enriched in proteins with extensive, interrupted coiled coil forming domains. The increased occurrence of this type of protein in metazoa compared with plants or protists leads us to hypothesize a tissue-wide matrix of coiled coil interactions underlying metazoan differentiated cell and tissue structure.
我们使用七肽重复分析程序检查了GenBank序列文件，以评估卷曲螺旋蛋白的系统发生情况、七肽重复结构域在其中的组织方式以及它们所包含的结构/功能类别。在分析的102,007种蛋白质中，5.95%（6,074种）含有卷曲螺旋结构域；1.26%（1,289种）含有“延伸的”（>75个氨基酸）结构域。虽然含有卷曲螺旋的蛋白质的频率在所有生物群中出人意料地恒定，但延伸的卷曲螺旋蛋白在动物界中的频率高出四倍，这可能反映了动植物分化早期的事件。延伸卷曲螺旋的结构/功能类别也揭示了系统发生差异。在病原体和寄生虫中，许多延伸的卷曲螺旋蛋白位于外部并与宿主蛋白结合。在动物中，大多数延伸的卷曲螺旋蛋白被鉴定为两类蛋白质的组成部分：1）肌球蛋白和马达蛋白；或2）核基质-中间丝支架的组成部分。这种支架是通过原位连续提取上皮单层产生的，仅占细胞质量的1-2%，同时准确保留了活上皮的形态特征，并且富含具有广泛、间断的卷曲螺旋形成结构域的蛋白质。与植物或原生生物相比，后生动物中这类蛋白质的出现增加，这使我们推测后生动物分化细胞和组织结构的基础是组织范围内的卷曲螺旋相互作用基质。
