Spieth J, Denison K, Zucker E, Blumenthal T
Nucleic Acids Res. 1985 Oct 11;13(19):7129-38. doi: 10.1093/nar/13.19.7129.
The nematode, Caenorhabditis elegans, contains a family of six genes that code for vitellogenins. Here we report the complete nucleotide sequence of one of these genes, vit-5. The gene specifies a mRNA of 4869 nucleotides, including untranslated regions of 9 bases at the 5' end and 51 bases at the 3' end. Vit-5 contains four short introns totalling 218 bp. The predicted vitellogenin, yp170A, has a molecular weight of 186,430. At its N terminus it is clearly related to the vitellogenins of vertebrates. However, the vit-5-encoded protein does not contain a serine-rich sequence related to the vertebrate vitellin, phosvitin. In fact, the amino acid composition of the nematode protein is very similar to that of the vertebrate protein without phosvitin. Vit-5 has a highly asymmetric codon choice dictionary. The favored codons are different from those favored in other organisms, but are characteristic of highly expressed C. elegans genes. The strong selection against rare codons is not as great near the 5' end of the gene; rare codons are 15 times more frequent within the first 54 bp than in the next 4.8 kb.
线虫秀丽隐杆线虫含有一个由六个基因组成的家族，这些基因编码卵黄原蛋白。在此，我们报告其中一个基因vit-5的完整核苷酸序列。该基因编码一个4869个核苷酸的mRNA，包括5'端9个碱基和3'端51个碱基的非翻译区。Vit-5含有四个短内含子，总长218 bp。预测的卵黄原蛋白yp170A的分子量为186,430。在其N端，它与脊椎动物的卵黄原蛋白明显相关。然而，由vit-5编码的蛋白质不包含与脊椎动物卵黄磷蛋白相关的富含丝氨酸的序列。实际上，线虫蛋白质的氨基酸组成与不含卵黄磷蛋白的脊椎动物蛋白质非常相似。Vit-5具有高度不对称的密码子选择字典。其偏好的密码子与其他生物中偏好的密码子不同，但却是高度表达的秀丽隐杆线虫基因的特征。在基因的5'端附近，对稀有密码子的强烈选择作用没有那么大；在前54 bp内，稀有密码子的出现频率比接下来的4.8 kb高15倍。
