Crouch D H, Gallagher R, Goding C R, Neil J C, Fulton R
Beatson Institute for Cancer Research, CRC Beatson Laboratories, Bearsden, Glasgow.
Nucleic Acids Res. 1996 Aug 15;24(16):3216-21. doi: 10.1093/nar/24.16.3216.
Chimaeric alleles were constructed to assay the biological functions of an N-terminal deletion and C-terminal mutations which were found in a naturally occurring mutant of feline vMyc, T17. The mutant alleles were assayed for their ability to transform chick embryo fibroblasts in vitro by a number of criteria, namely the ability to induce morphological transformation, an accelerated growth rate and growth in soft agar. Feline cMyc could transform the avian cells, whilst T17 vMyc could not, and the N-terminal deletion was responsible for conferring the primary transformation defect on the mutant protein. The C-terminal mutations which consist of a point mutation adjacent to the nuclear localisation signal and a point mutation/amino acid insertion within the basic region (BR) could, however, dissociate the Myc-induced parameters of transformation. This effect was a specific function of the BR mutation alone, and the mutation could be transferred into avian cMyc with comparable biological consequences. The BR mutation did not disrupt the sequence specific DNA binding activity of the protein in vivo, despite exerting a biological effect. These data suggest a novel phenotype where the mutation may affect a subset of Myc-regulated genes through altered DNA binding specificity or protein-protein interactions.
构建了嵌合等位基因，以分析在猫科动物vMyc的天然突变体T17中发现的N端缺失和C端突变的生物学功能。通过一些标准来检测突变等位基因在体外转化鸡胚成纤维细胞的能力，即诱导形态转化的能力、加速生长速率以及在软琼脂中生长的能力。猫科动物cMyc能够转化禽类细胞，而T17 vMyc则不能，并且N端缺失是导致突变蛋白出现主要转化缺陷的原因。然而，由与核定位信号相邻的点突变以及碱性区域（BR）内的点突变/氨基酸插入组成的C端突变，能够使Myc诱导的转化参数解离。这种效应仅是BR突变的特定功能，并且该突变可以转移到禽类cMyc中，产生类似的生物学后果。尽管BR突变发挥了生物学效应，但它并未在体内破坏该蛋白的序列特异性DNA结合活性。这些数据表明了一种新的表型，其中该突变可能通过改变DNA结合特异性或蛋白质-蛋白质相互作用来影响Myc调控基因的一个子集。
