MURINE HELIX-LOOP-HELIX TRANSCRIPTIONAL ACTIVATOR PROTEINS BINDING TO THE E-BOX MOTIF OF THE AKV MURINE LEUKEMIA-VIRUS ENHANCER IDENTIFIED BY CDNA CLONING
MURINE HELIX-LOOP-HELIX TRANSCRIPTIONAL ACTIVATOR PROTEINS BINDING TO THE E-BOX MOTIF OF THE AKV MURINE LEUKEMIA-VIRUS ENHANCER IDENTIFIED BY CDNA CLONING
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DOI：
10.1128/mcb.12.8.3449
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发表时间：
1992-08-01
影响因子：
5.3
通讯作者：
JORGENSEN, P
中科院分区：
文献类型：
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作者：
NIELSEN, AL;PALLISGAARD, N;JORGENSEN, P
AKV小鼠白血病病毒增强子区域含有序列基序ACAGATGG。该序列与E-box基序同源，E-box基序最初被定义为免疫球蛋白u和kappa基因增强子中的调节元件。我们使用与小鼠白血病病毒Akv的E盒相对应的双链寡核苷酸探针，从小鼠NIH3T3成纤维细胞RNA中筛选出随机启动的lambda-gt11表达文库。我们已经鉴定了七个表达DNA结合蛋白的Lambda克隆，分别代表两个不同的基因ALF1和ALF2。对ALF2基因的测序结果表明，我们已经恢复了碱性-螺旋-环-螺旋转录因子A1的基因，这是人类转录因子E47的小鼠类似物。ALF1基因编码碱性-螺旋-环-螺旋蛋白家族的一个新成员。已发现ALF1基因的两个剪接变异体，不同的是72bp的插入，编码682和706个氨基酸的推测蛋白质。这两个ALF1mRNAs在小鼠组织中有不同程度的表达。利用原核表达的ALF1蛋白进行的体外DNA结合试验表明，ALF1蛋白与Akv小鼠白血病病毒E盒基序ACAGATGG特异结合。在NIH 3T3成纤维细胞中表达GAL4-ALF1嵌合蛋白可刺激与GAL4结合位点相连的最小启动子的表达，表明ALF1中存在转录激活域。
The enhancer region of Akv murine leukemia virus contains the sequence motif ACAGATGG. This sequence is homologous to the E-box motif originally defined as a regulatory element in the enhancers of immunoglobulin mu and kappa genes. We have used double-stranded oligonucleotide probes, corresponding to the E box of the murine leukemia virus Akv, to screen a randomly primed lambda-gt11 cDNA expression library made from mouse NIH 3T3 fibroblast RNA. We have identified seven lambda clones expressing DNA-binding proteins representing two different genes termed ALF1 and ALF2. The results of sequencing ALF2 cDNA suggests that we have recovered the gene for the basic-helix-loop-helix transcription factor A1, the murine analog of the human transcription factor E47. The cDNA sequence of ALF1 codes for a new member of the basic-helix-loop-helix protein family. Two splice variants of ALF1 cDNA have been found, differing by a 72-bp insertion, coding for putative proteins of 682 and 706 amino acids. The two ALF1 mRNAs are expressed at various levels in mouse tissues. In vitro DNA binding assays, using prokaryotically expressed ALF1 proteins, demonstrated specific binding of the ALF1 proteins to the Akv murine leukemia virus E-box motif ACAGATGG. Expression in NIH 3T3 fibroblasts of GAL4-ALF1 chimeric protein stimulated expression from a minimal promoter linked to a GAL4 binding site, indicating the existence of a transcriptional activator domain in ALF1.