Descombes P, Schibler U
Département de Biologie Moléculaire Sciences II, Geneve, Switzerland.
Cell. 1991 Nov 1;67(3):569-79. doi: 10.1016/0092-8674(91)90531-3.
LAP, a transcriptional activator, and LIP, a transcriptional repressor, are translated from a single mRNA species by using two AUGs within the same reading frame. These two proteins share the 145 C-terminal amino acids that contain the basic DNA-binding domain and the leucine zipper dimerization helix. Probably owing to its higher affinity for its DNA cognate sequences, LIP can attenuate the transcriptional stimulation by LAP in substoichiometric amounts. As revealed by transient transfection experiments, a moderate increase in the LAP/LIP ratio results in a significantly higher transcriptional activation of an appropriate target gene. The LAP/LIP ratio increases about 5-fold during terminal rat liver differentiation and is thus likely to modulate the activity of LAP in the intact animal.
LAP是一种转录激活因子，而LIP是一种转录抑制因子，它们通过使用同一阅读框内的两个AUG，从单一mRNA转录本翻译而来。这两种蛋白质共享145个C端氨基酸，其中包含碱性DNA结合结构域和亮氨酸拉链二聚化螺旋。可能由于LIP对其DNA同源序列具有更高的亲和力，它能够以亚化学计量的量减弱LAP的转录刺激作用。瞬时转染实验表明，LAP/LIP比值适度增加会导致合适的靶基因转录激活显著增强。在大鼠肝脏终末分化过程中，LAP/LIP比值增加约5倍，因此很可能在完整动物体内调节LAP的活性。
