Lau J T, Lennarz W J
Proc Natl Acad Sci U S A. 1983 Feb;80(4):1028-32. doi: 10.1073/pnas.80.4.1028.
Gastrulation in sea urchin embryos is accompanied by a striking increase in the synthesis of N-linked glycoproteins, and inhibitors of this process block gastrulation. In this report, the messages coding for N-glycosylatable proteins in the developing embryo of the sea urchin, Strongylocentrotus purpuratus, were examined. Total mRNA and mRNA isolated from membranes of the embryos at various stages of development were used to program a cell-free translation/glycosylation system prepared from rabbit reticulocyte lysate supplemented with dog pancreas microsomes. The glycosylated translation products were separated from the nonglycosylated products by concanavalin A-agarose and analyzed by gel electrophoresis. The results indicate that although the RNA derived from the membranes of gastrula-stage embryos contains messages coding for numerous glycoproteins, only trace amounts of glycoprotein messages are associated with membranes at earlier stages of development. mRNAs coding for four glycoproteins of M(r)s 70,000, 65,000, 51,000, and 30,000 were examined further in total RNA preparations from the developing embryo. The data indicate that the messages coding for the glycoproteins of M(r)s 65,000 and 51,000 are present also in the unfertilized egg and in the pregastrulation embryo. Because these two messages are not found associated with the membranes until gastrula stage, it is likely that the synthesis of these glycoproteins during gastrulation is regulated at the translational level. The messages coding for glycoproteins of M(r)s 70,000 and 30,000, on the other hand, are not detectable in the unfertilized egg and may be synthesized de novo by the embryos. Thus, the expression of these two glycoproteins during gastrulation is regulated at least in part on the transcriptional level. On the basis of these findings, it appears that different modes of regulation are used for different glycoproteins that are synthesized during gastrulation.
海胆胚胎的原肠胚形成伴随着N-连接糖蛋白合成的显著增加，并且这一过程的抑制剂会阻断原肠胚形成。在本报告中，对紫球海胆（Strongylocentrotus purpuratus）发育胚胎中编码N-糖基化蛋白的信息进行了研究。从胚胎发育各个阶段的膜中分离得到的总mRNA和mRNA，被用于对由补充了狗胰腺微粒体的兔网织红细胞裂解物制备的无细胞翻译/糖基化系统进行编程。糖基化的翻译产物通过伴刀豆球蛋白A-琼脂糖与非糖基化产物分离，并通过凝胶电泳进行分析。结果表明，尽管来自原肠胚期胚胎膜的RNA包含编码众多糖蛋白的信息，但在发育早期阶段，只有微量的糖蛋白信息与膜相关。在发育胚胎的总RNA制剂中，进一步研究了编码分子量为70,000、65,000、51,000和30,000的四种糖蛋白的mRNA。数据表明，编码分子量为65,000和51,000的糖蛋白的信息也存在于未受精卵和原肠胚形成前的胚胎中。由于直到原肠胚期才发现这两种信息与膜相关，因此这些糖蛋白在原肠胚形成期间的合成可能在翻译水平受到调控。另一方面，编码分子量为70,000和30,000的糖蛋白的信息在未受精卵中无法检测到，可能是由胚胎重新合成的。因此，这两种糖蛋白在原肠胚形成期间的表达至少部分在转录水平受到调控。基于这些发现，似乎在原肠胚形成期间合成的不同糖蛋白使用了不同的调控模式。
