Campbell H D, Schimansky T, Claudianos C, Ozsarac N, Kasprzak A B, Cotsell J N, Young I G, de Couet H G, Miklos G L
Research School of Biological Sciences, Australian National University, Canberra.
Proc Natl Acad Sci U S A. 1993 Dec 1;90(23):11386-90. doi: 10.1073/pnas.90.23.11386.
Mutations at the flightless-I locus (fliI) of Drosophila melanogaster cause flightlessness or, when severe, incomplete cellularization during early embryogenesis, with subsequent abnormalities in mesoderm invagination and in gastrulation. After chromosome walking, deficiency mapping, and transgenic analysis, we have isolated and characterized flightless-I cDNAs, enabling prediction of the complete amino acid sequence of the 1256-residue protein. Data base searches revealed a homologous gene in Caenorhabditis elegans, and we have isolated and characterized corresponding cDNAs. By using the polymerase chain reaction with nested sets of degenerate oligonucleotide primers based on conserved regions of the C. elegans and D. melanogaster proteins, we have cloned a homologous human cDNA. The predicted C. elegans and human proteins are, respectively, 49% and 58% identical to the D. melanogaster protein. The predicted proteins have significant sequence similarity to the actin-binding protein gelsolin and related proteins and, in addition, have an N-terminal domain consisting of a repetitive amphipathic leucine-rich motif. This repeat is found in D. melanogaster, Saccharomyces cerevisiae, and mammalian proteins known to be involved in cell adhesion and in binding to other proteins. The structure of the maternally expressed flightless-I protein suggests that it may play a key role in embryonic cellularization by interacting with both the cytoskeleton and other cellular components. The presence of a highly conserved homologue in nematodes, flies, and humans is indicative of a fundamental role for this protein in many metazoans.
果蝇黑腹果蝇（Drosophila melanogaster）中无翅基因座（fliI）的突变会导致无法飞行，或者在严重时，会在胚胎早期发育过程中导致细胞化不完全，随后中胚层内陷和原肠胚形成出现异常。经过染色体步移、缺失定位和转基因分析，我们分离并鉴定了无翅基因的cDNA，从而能够预测出1256个氨基酸残基蛋白质的完整氨基酸序列。数据库搜索揭示了秀丽隐杆线虫（Caenorhabditis elegans）中有一个同源基因，我们也分离并鉴定了相应的cDNA。通过使用基于秀丽隐杆线虫和果蝇黑腹果蝇蛋白质保守区域的嵌套简并寡核苷酸引物进行聚合酶链反应，我们克隆了一个同源的人类cDNA。预测的秀丽隐杆线虫和人类蛋白质分别与果蝇黑腹果蝇蛋白质有49%和58%的同一性。预测的蛋白质与肌动蛋白结合蛋白凝溶胶蛋白及相关蛋白有显著的序列相似性，此外，还有一个由重复的两亲性富含亮氨酸基序组成的N端结构域。这种重复结构存在于果蝇黑腹果蝇、酿酒酵母（Saccharomyces cerevisiae）以及已知参与细胞黏附及与其他蛋白质结合的哺乳动物蛋白质中。母源表达的无翅蛋白的结构表明，它可能通过与细胞骨架和其他细胞成分相互作用，在胚胎细胞化过程中发挥关键作用。线虫、果蝇和人类中存在高度保守同源物，这表明该蛋白在许多后生动物中具有重要作用。
