Identification of EFIV, a stable factor present in many avian cell types that transactivates sequences in the 5' portion of the Rous sarcoma virus long terminal repeat enhancer.
Identification of EFIV, a stable factor present in many avian cell types that transactivates sequences in the 5' portion of the Rous sarcoma virus long terminal repeat enhancer.
复制标题
EFIV 的鉴定，EFIV 是一种存在于许多鸟类细胞类型中的稳定因子，可反式激活劳斯肉瘤病毒长末端重复增强子 5 部分的序列。
DOI：
10.1128/jvi.70.1.393-401.1996
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Conklin,KF
中科院分区：
文献类型：
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作者：
Houtz,EK;Conklin,KF
我们定义了一种存在于禽核提取物中的蛋白复合物，该蛋白复合物与劳斯肉瘤病毒（RSV）长末端重复序列（LTR）的施密特-鲁平株在相对于转录起始位点的位置-197和-168之间相互作用。我们称这种复合体为EFIV，并证明EFIV蛋白存在于所检查的几种禽类细胞类型中，包括B细胞（S13和DT 40）、T细胞（MS B）和鸡胚成纤维细胞。我们还报告了EFIV结合位点在转染入禽B细胞和鸡胚成纤维细胞后激活报告构建体的转录，表明EFIV区域构成功能性反式激活因子序列。通过化学干扰足迹法和突变分析，我们将EFIV结合位点定义为包括序列GCAACATG，其存在于位置-197和-168之间的两个拷贝中，以及位于两个重复之间的序列。电泳迁移率改变竞争实验表明EFIV蛋白可能与CCAAT/增强子结合蛋白家族的转录因子相关，这些转录因子与RSV和禽白血病病毒（ALV）LTR的不同区域相互作用。然而，如通过对蛋白质合成抑制剂的敏感性和足迹模式的差异所定义的，EFIV明显不同于这些先前定义的LTR结合因子。此外，EFIV结合活性在B细胞中稳定的发现表明，所有5' LTR结合活性的不稳定性不是ALV/RSV病毒家族转化B细胞所必需的，或者包括RSV LTR的非急性转化病毒可能使用与针对ALV提出的机制不同的机制来实现细胞转化。
We define a protein complex present in avian nuclear extracts that interacts with the Schmidt-Ruppin strain of the Rous sarcoma virus (RSV) long terminal repeat (LTR) between positions -197 and -168 relative to the transcriptional start site. We call this complex EFIV and demonstrate that the EFIV protein(s) is present in several avian cell types examined, including B cells (S13 and DT40), T cells (MSB), and chicken embryo fibroblasts. We also report that the EFIV binding site activates transcription of reporter constructs after transfection into avian B cells and chicken embryo fibroblasts, demonstrating that the EFIV region constitutes a functional transactivator sequence. By chemical interference footprinting and mutational analyses we define the EFIV binding site as including the sequence GCAACATG, which is present in two copies between positions -197 and -168, as well as sequences that lie between the two repeats. Electrophoretic mobility shift competition experiments suggest that the EFIV protein(s) may be related to members of the CCAAT/enhancer-binding protein family of transcription factors that interact with different regions of the RSV and the avian leukosis virus (ALV) LTRs. However, as defined by differences in sensitivity to protein synthesis inhibitors and footprinting patterns, EFIV is clearly distinct from these previously defined LTR binding factors. In addition, the finding that EFIV binding activity is stable in B cells indicates either that the lability of all 5' LTR binding activities is not required for B-cell transformation by the ALV/RSV family of viruses or that nonacute transforming viruses that include an RSV LTR may use a mechanism to effect cellular transformation different from that proposed for ALV.