Lane T, Ibanez C, Garcia A, Graf T, Lipsick J
Department of Pathology, University of California, San Diego, La Jolla 92093.
Mol Cell Biol. 1990 Jun;10(6):2591-8. doi: 10.1128/mcb.10.6.2591-2598.1990.
The v-myb oncogene of avian myeloblastosis virus causes acute myelomonocytic leukemia in chickens and transforms avian myeloid cells in vitro. Its protein product p48v-myb is a nuclear, sequence-specific, DNA-binding protein which activates gene expression in transient DNA transfection studies. To investigate the relationship between transformation and trans-activation by v-myb, we constructed 15 in-frame linker insertion mutants. The 12 mutants which transformed myeloid cells also trans-activated gene expression, whereas the 3 mutants which did not transform also did not trans-activate. This implies that trans-activation is required for transformation by v-myb. One of the transformation-defective mutants localized to the cell nucleus but failed to bind DNA. The other two transformation-defective mutants localized to the cell nucleus and bound DNA but nevertheless failed to trans-activate. These latter mutants define two distinct domains of p48v-myb which control trans-activation by DNA-bound protein, one within the amino-terminal DNA-binding domain itself and one in a carboxyl-terminal domain which is not required for DNA binding.
禽成髓细胞瘤病毒的v-myb癌基因可在鸡中引发急性髓单核细胞白血病，并在体外使禽髓细胞发生转化。其蛋白质产物p48v-myb是一种核内、序列特异性的DNA结合蛋白，在瞬时DNA转染研究中可激活基因表达。为了研究v-myb介导的转化作用与反式激活之间的关系，我们构建了15个读码框内的接头插入突变体。其中12个能转化髓细胞的突变体也能反式激活基因表达，而另外3个不能转化的突变体也不能反式激活。这表明反式激活是v-myb介导转化所必需的。其中一个转化缺陷型突变体定位于细胞核，但无法结合DNA。另外两个转化缺陷型突变体定位于细胞核且能结合DNA，但仍无法反式激活。后一类突变体确定了p48v-myb的两个不同结构域，它们控制着由DNA结合蛋白介导的反式激活，一个在氨基末端DNA结合结构域本身内，另一个在羧基末端结构域，该结构域对于DNA结合并非必需。
