Kovary K, Bravo R
Department of Molecular Biology, Bristol-Myers Squibb Institute for Pharmaceutical Research, Princeton, New Jersey 08543-4000.
Mol Cell Biol. 1991 May;11(5):2451-9. doi: 10.1128/mcb.11.5.2451-2459.1991.
We have characterized the expression of c-Jun, JunB, JunD, c-Fos, and FosB proteins following serum stimulation of quiescent Swiss 3T3 cells by immunoprecipitation analyses. The synthesis of the three Jun proteins rapidly increases following stimulation, remaining at a significant level for at least 8 h. JunB protein presents the highest expression of all. FosB, like c-Fos, is transiently induced. Pulse-chase experiments show that all of the proteins except JunD are short-lived. We have shown that c-Fos and FosB form complexes in vivo with the different Jun proteins and that JunB complexes are predominant. In vitro association and competition experiments show that the affinities between the different Fos and Jun proteins are similar. This finding, together with the in vivo observations described above, suggests that the proportion of the different Jun/Fos heterodimers is governed by the concentration of the different components. The Fos and Jun proteins are phosphoproteins, and some remain relatively highly phosphorylated in their heterodimeric form.
我们通过免疫沉淀分析，对静止的瑞士3T3细胞进行血清刺激后c-Jun、JunB、JunD、c-Fos和FosB蛋白的表达进行了表征。刺激后，三种Jun蛋白的合成迅速增加，并在至少8小时内保持在显著水平。JunB蛋白的表达在所有蛋白中最高。FosB与c-Fos一样，是短暂诱导产生的。脉冲追踪实验表明，除JunD外，所有蛋白的寿命都很短。我们已经证明，c-Fos和FosB在体内与不同的Jun蛋白形成复合物，且JunB复合物占主导地位。体外结合和竞争实验表明，不同的Fos和Jun蛋白之间的亲和力相似。这一发现与上述体内观察结果表明，不同Jun/Fos异二聚体的比例受不同组分浓度的控制。Fos和Jun蛋白是磷蛋白，其中一些在异二聚体形式下仍保持相对较高的磷酸化水平。
