Lyons R H, Ferguson B Q, Rosenberg M
Mol Cell Biol. 1987 Jul;7(7):2451-6. doi: 10.1128/mcb.7.7.2451-2456.1987.
The adenovirus E1a gene products are nuclear proteins important in transcriptional control of viral functions during infection. By producing normal E1a proteins and derivatives of E1a in bacteria and microinjecting these proteins into cultured cells, we were able to examine their ability to localize to the nucleus. We showed that a short peptide sequence at the carboxyl terminus of E1a is necessary for the rapid (30-min) nuclear localization of that protein. Additionally, we showed that just the last five amino acids of E1a are sufficient to direct nuclear accumulation of a heterologous protein, Escherichia coli galactokinase, with the same kinetics as native E1a. The mechanism by which this pentamer mediates rapid nuclear localization was examined by testing the ability of a galactokinase derivative which has no signal pentamer to exit the nucleus, as well as to enter it. Because neither free entry nor exit was detected, the effect of the signal is unlikely to be through increased nuclear retention of freely diffusible proteins but rather by enhancement of entry into the nucleus.
腺病毒E1a基因产物是核蛋白，在感染期间对病毒功能的转录控制很重要。通过在细菌中产生正常的E1a蛋白和E1a衍生物，并将这些蛋白显微注射到培养细胞中，我们能够检测它们定位于细胞核的能力。我们发现，E1a羧基末端的一段短肽序列对于该蛋白快速（30分钟）定位于细胞核是必需的。此外，我们还发现，E1a的最后五个氨基酸就足以指导异源蛋白大肠杆菌半乳糖激酶的核积累，其动力学与天然E1a相同。通过测试没有信号五聚体的半乳糖激酶衍生物离开细胞核以及进入细胞核的能力，研究了这个五聚体介导快速核定位的机制。由于未检测到自由进入或离开，信号的作用不太可能是通过增加可自由扩散蛋白在细胞核中的滞留，而是通过增强进入细胞核的能力。
