van Klaveren P, Bentvelzen P
Department of Retrovirology, Radiobiological Institute, Rijswijk, The Netherlands.
J Virol. 1988 Nov;62(11):4410-3. doi: 10.1128/JVI.62.11.4410-4413.1988.
The procaryotic chloramphenicol acetyltransferase (CAT) gene controlled by the murine mammary tumor virus (MMTV) promoter shows reduced activity in a rat mammary tumor cell line after infection with MMTV but to a considerably lesser extent than the CAT gene controlled by a heterologous promoter, indicating trans-acting regulation of promoter activity by MMTV. Cotransfection of vectors capable of expressing RNA from the 3' open reading frame (orf) of MMTV with the CAT-MMTV construct resulted in enhanced CAT activity, suggesting that orf carries a transactivating potential. Since transactivation was also found with a vector containing only orf and part of the viral env gene, it was concluded that a separate transcriptional unit exists for the orf message.
由鼠乳腺肿瘤病毒（MMTV）启动子控制的原核氯霉素乙酰转移酶（CAT）基因，在MMTV感染后的大鼠乳腺肿瘤细胞系中活性降低，但程度远小于由异源启动子控制的CAT基因，这表明MMTV对启动子活性存在反式作用调控。将能够从MMTV的3'开放阅读框（orf）表达RNA的载体与CAT-MMTV构建体共转染，导致CAT活性增强，这表明orf具有反式激活潜力。由于在仅包含orf和部分病毒env基因的载体中也发现了反式激活，因此得出结论，orf信息存在一个单独的转录单元。
