Gimlich R L, Kumar N M, Gilula N B
Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, California 92037.
J Cell Biol. 1988 Sep;107(3):1065-73. doi: 10.1083/jcb.107.3.1065.
Cloned complementary DNAs representing the complete coding sequence for an embryonic gap junction protein in the frog Xenopus laevis have been isolated and sequenced. The cDNAs hybridize with an RNA of 1.5 kb that is first detected in gastrulating embryos and accumulates throughout gastrulation and neurulation. By the tailbud stage, the highest abundance of the transcript is found in the region containing ventroposterior endoderm and the rudiment of the liver. In the adult, transcripts are present in the lungs, alimentary tract organs, and kidneys, but are not detected in the brain, heart, body wall and skeletal muscles, spleen, or ovary. The gene encoding this embryonic gap junction protein is present in only one or a few copies in the frog genome. In vitro translation of RNA synthesized from the cDNA template produces a 30-kD protein, as predicted by the coding sequence. This product has extensive sequence similarity to mammalian gap junction proteins in its putative transmembrane and extracellular domains, but has diverged substantially in two of its intracellular domains.
已分离并测序了代表非洲爪蟾胚胎缝隙连接蛋白完整编码序列的克隆互补DNA。这些cDNA与1.5 kb的RNA杂交，该RNA最早在原肠胚形成期的胚胎中被检测到，并在整个原肠胚形成期和神经胚形成期积累。到尾芽期，转录本的最高丰度出现在包含腹后端内胚层和肝脏原基的区域。在成体中，转录本存在于肺、消化道器官和肾脏中，但在脑、心脏、体壁和骨骼肌、脾脏或卵巢中未检测到。编码这种胚胎缝隙连接蛋白的基因在蛙基因组中仅以一个或几个拷贝存在。从cDNA模板合成的RNA的体外翻译产生了一个30-kD的蛋白质，正如编码序列所预测的那样。该产物在其假定的跨膜和细胞外结构域与哺乳动物缝隙连接蛋白具有广泛的序列相似性，但在其两个细胞内结构域中发生了很大的分化。
