VITELLOGENIN MOTIFS CONSERVED IN NEMATODES AND VERTEBRATES
VITELLOGENIN MOTIFS CONSERVED IN NEMATODES AND VERTEBRATES
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DOI：
10.1007/bf02101283
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发表时间：
1991-05-01
影响因子：
3.9
通讯作者：
BLUMENTHAL, T
中科院分区：
文献类型：
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作者：
SPIETH, J;NETTLETON, M;BLUMENTHAL, T
秀丽隐杆线虫卵黄原蛋白是由一个家族的6个基因，其中之一，维生素5，已被测序，并显示出惊人的密切相关的脊椎动物卵黄原蛋白基因。 本文报道了蛙和鸡卵黄原蛋白的氨基酸序列与三种C. elegans基因：vit-5和两个新测序的基因vit-2和vit-6。 vit-6的4个内含子与vit-5的4个内含子的位置不同，但其中3个位置与脊椎动物卵黄蛋白原基因的内含子位置相同或接近。 所编码的多肽彼此之间的差异足以使我们得出一些关于保守位置的结论。 许多半胱氨酸残基是保守的，这表明卵黄蛋白原的结构已经保持了很长的进化距离，并依赖于二硫键。 此外，20个残基的片段显示脊椎动物和线虫卵黄原蛋白之间的保守性。 该序列可能在卵黄发生中发挥高度保守的作用，例如被卵母细胞特异性识别。 然而，总的来说，选择可能对氨基酸组成和密码子使用的作用比对氨基酸序列的作用更强，正如对丰富的贮藏蛋白质所预期的那样：vit-2、vit-5和vit-6产物的氨基酸组成非常相似，尽管事实上Vit-2蛋白的序列分别与Vit-6和Vit-5蛋白的序列仅22%和50%相同。
Caenorhabditis elegans vitellogenins are encoded by a family of six genes, one of which, vit-5, has been previously sequenced and shown to be surprisingly closely related to the vertebrate vitellogenin genes. Here we report an alignment of the amino acid sequences of vitellogenins from frog and chicken with those from three C. elegans genes: vit-5 and two newly sequenced genes, vit-2 and vit-6. The four introns of vit-6 are all in different places from the four introns of vit-5, but three of these eight positions are identical or close to intron locations in the vertebrate vitellogenin genes. The encoded polypeptides have diverged from one another sufficiently to allow us to draw some conclusions about conserved positions. Many cysteine residues have been conserved, suggesting that vitellogenin structure has been maintained over a long evolutionary distance and is dependent upon disulfide bonds. In addition, a 20-residue segment shows conservation between the vertebrate and the nematode vitellogenins. This sequence may play a highly conserved role in vitellogenesis, such as specific recognition by oocytes. On the whole, however, selection may be acting more strongly on amino acid composition and codon usage than on amino acid sequence, as might be expected for abundant storage proteins: The amino acid compositions of vit-2, vit-5, and vit-6 products are remarkably similar, despite the fact that the sequence of the vit-2 protein is only 22% and 50% identical to the sequences of vit-6 and vit-5 proteins, respectively.