Spieth J, Blumenthal T
Mol Cell Biol. 1985 Oct;5(10):2495-501. doi: 10.1128/mcb.5.10.2495-2501.1985.
While the nematode Caenorhabditis elegans is more primitive than most egg-laying organisms, it's vitellogenins, or yolk protein precursors, appear to be more complex. C. elegans oocytes accumulate two major classes of yolk proteins. The first consists of two polypeptides with an Mr of about 170,000 (yp170A and yp170B) encoded by a family of five closely related genes called vit-1 through vit-5. The second class consists of two smaller proteins with Mr values of 115,000 (yp115) and 88,000 (yp88) which are cut from a single precursor. Here we report the cloning and analysis of a single-copy gene (vit-6) that encodes this precursor. The lengths of the gene and its mRNA are about 5 X 10(3) base pairs. Like vit-1 through vit-5, vit-6 is expressed exclusively in adult hermaphrodites. Comparison of portions of the coding sequence indicates that vit-6 is distantly related to the vit-1 through vit-5 gene family. Thus, even though the two classes of yolk proteins are antigenically and physically distinct, they are encoded by a single highly diverged gene family.
虽然线虫秀丽隐杆线虫比大多数产卵生物更原始，但其卵黄生成素或卵黄蛋白前体似乎更为复杂。秀丽隐杆线虫的卵母细胞积累两类主要的卵黄蛋白。第一类由两个分子量约为170,000的多肽（yp170A和yp170B）组成，它们由一个由五个紧密相关的基因家族（称为vit-1至vit-5）编码。第二类由两个较小的蛋白质组成，分子量分别为115,000（yp115）和88,000（yp88），它们是从单个前体切割而来的。在此我们报告了一个编码该前体的单拷贝基因（vit-6）的克隆和分析。该基因及其mRNA的长度约为5×10³碱基对。与vit-1至vit-5一样，vit-6仅在成年雌雄同体中表达。编码序列部分的比较表明，vit-6与vit-1至vit-5基因家族关系较远。因此，即使这两类卵黄蛋白在抗原性和物理性质上不同，但它们由一个高度分化的单一基因家族编码。
