GENES ANCESTRAL TO THE THYROID/STEROID RECEPTOR FAMILY

这个项目的目的是确定最早的系统发育 甲状腺/类固醇激素受体家族基因的出现， 以便更好地了解其功能。 超过30名成员 这个基因家族是已知的，但很少有数据表明它们发生在 原始形态 这些基因产物中的许多，尽管它们具有 配体结合域没有已知配体。 为了获得克隆体， 使用涉及DNA结合结构域的简并引物， 并设计了包括PCR在内的程序， 可以有效克隆相关基因。 我们先前已经 分离出了美杜莎的序列，但迄今为止还无法得到完整的序列。 长度cDNA。 我们从玻璃海鞘中分离到三个克隆， 意大利的Janinni目前正在研究其中的一种。我们现在已经 分离并完全测序了三个来自秀丽线虫的cDNA（一个原始的 蛔虫）。 这些克隆之一（ce 3）显示最高的氨基酸同源性 DHR 3是果蝇蜕皮激素反应基因之一 另一个，ce 8 与早期人类应答基因（nak 1）的同源性较低， 但与NOT 1具有显著的同源性，NOT 1是一种酵母的一般负调节因子， 转录。 Ce 14与视黄酸受体同源性最高 基因 DNA结合结构域之外的所有同源性都很低， 我们描述的基因似乎是这个家族的新成员。 北方 分析表明，ce 3和ce 8在胚胎中高度表达， 幼虫阶段 这三种基因的表达程度大致相同 在成年人中。 在原位杂交的初步实验中， 洋地黄毒苷标记的核糖探针和与碱缀合的抗体 磷酸酶，得到类似于Norther实验的结果。

The aim of this project is to determine the earliest phylogenetic occurrence of genes of the Thyroid/Steroid hormone receptor family in order to better understand their function. More than thirty members of this gene family are known but there are few data on their occurrence in primitive forms. Many of these gene products, although they possess a ligand binding domain have no known ligands. To obtain clones we have used degenerate primers involving the DNA binding domain which is well preserved in this family, and have devised procedures including PCR to allow efficient cloning of the relevant genes. We have previously isolated a sequence for medusa but have so far been unable to get a full length cDNA. We isolated three clones from ciona intestinalis and Dr. Janinni in Italy is currently working on one of them. We have now isolated and completely sequenced three cDNAs from C elegans (a primitive round worm). One of these clones (ce3) shows highest amino acid homology to DHR 3, one of the ecdysone response genes in drosophila. Another, ce8 shows lesser homology to an early human response gene(nak1), and a low but significant homology to NOT1, a yeast general negative regulator of transcription. Ce14 is most homologous to the retinoic acid receptor gene. All the homologies outside the DNA binding domain are so low that the genes we describe appear to be new members of this family. Northern analysis shows that ce3 and ce8 are highly expressed in embryos and in larval stages. All three genes are expressed to about the same extent in adults. In preliminary experiments with in situ hybridization using a digoxigenin labelled riboprobe and an antibody conjugated with alkaline phosphatase, results similar to the Norther experiments were obtained.