Yen J, Wisdom R M, Tratner I, Verma I M
Molecular Biology and Virology Laboratory, Salk Institute, San Diego, CA 92186-5800.
Proc Natl Acad Sci U S A. 1991 Jun 15;88(12):5077-81. doi: 10.1073/pnas.88.12.5077.
Two forms of FosB transcript and their products can be identified in mouse NIH 3T3 cells following serum induction. The larger RNA codes for a 338-amino acid protein, whereas the smaller RNA results from the removal of an additional 140 nucleotides from FosB mRNA by alternative splicing. This alternative splicing event places a stop codon following the "leucine zipper" region and results in a shorter protein (FosB2) of 237 amino acids that lacks 101 amino acids at the carboxyl terminus. FosB2 is able to form heterodimers with c-Jun and bind to an AP-1 site but is not able to activate the transcription of promoters containing AP-1 sites. Furthermore, FosB2 can not only suppress the transcriptional activation by c-Fos and c-Jun of promoters containing an AP-1 site but also interferes with the transforming potential of viral and cellular Fos proteins. We propose that FosB2 protein functions as a trans-negative regulator.
血清诱导后，在小鼠NIH 3T3细胞中可鉴定出两种形式的FosB转录本及其产物。较大的RNA编码一种338个氨基酸的蛋白质，而较小的RNA是通过可变剪接从FosB mRNA中去除额外的140个核苷酸产生的。这种可变剪接事件在“亮氨酸拉链”区域之后放置了一个终止密码子，从而产生了一种较短的237个氨基酸的蛋白质（FosB2），该蛋白质在羧基末端缺少101个氨基酸。FosB2能够与c-Jun形成异二聚体并结合到AP-1位点，但不能激活含有AP-1位点的启动子的转录。此外，FosB2不仅可以抑制含有AP-1位点的启动子被c-Fos和c-Jun转录激活，还能干扰病毒和细胞Fos蛋白的转化潜能。我们认为FosB2蛋白起反式负调节因子的作用。
