Ozaki T, Sakiyama S
Division of Biochemistry, Chiba Cancer Center Research Institute, Japan.
Proc Natl Acad Sci U S A. 1993 Apr 1;90(7):2593-7. doi: 10.1073/pnas.90.7.2593.
A differential screening procedure was used to isolate genes that are specifically down-regulated in transformed cells. After screening a cDNA library derived from normal rat fibroblast (3Y1) cells, we obtained several independent cDNAs whose mRNA level was substantially lower in 3Y1 cells transformed with Rous sarcoma virus than in untransformed 3Y1 cells. Among them, N03 cDNA has been characterized extensively. N03 mRNA was also absent from v-mos- or simian virus 40-transformed 3Y1 cells but was present in v-Ha-ras-transformed 3Y1 cells. Nucleotide sequence analysis showed that the N03 protein is composed of 178 amino acid residues and does not have any sequence similarities with proteins in the data base. A putative zinc-finger domain is located in the central part of the sequence and a proline-rich domain is in the C-terminal region. N03 mRNA was detected by Northern blot analysis in several tissues, including lung, kidney, intestine, and brain, but not in liver. Genomic Southern blot hybridization revealed that the N03 gene exists as a single copy in the rat genome and that closely related, single-copy genes are also present in chicken and human.
采用差异筛选程序分离在转化细胞中特异性下调的基因。在用来自正常大鼠成纤维细胞（3Y1）的cDNA文库进行筛选后，我们获得了几个独立的cDNA，其在经劳斯肉瘤病毒转化的3Y1细胞中的mRNA水平明显低于未转化的3Y1细胞。其中，N03 cDNA已被广泛表征。v-mos或猴病毒40转化的3Y1细胞中也不存在N03 mRNA，但在v-Ha-ras转化的3Y1细胞中存在。核苷酸序列分析表明，N03蛋白由178个氨基酸残基组成，与数据库中的蛋白质没有任何序列相似性。一个推定的锌指结构域位于序列的中部，富含脯氨酸的结构域位于C末端区域。通过Northern印迹分析在包括肺、肾、肠和脑在内的几种组织中检测到N03 mRNA，但在肝脏中未检测到。基因组Southern印迹杂交显示，N03基因在大鼠基因组中以单拷贝形式存在，鸡和人类中也存在密切相关的单拷贝基因。
