Simonen M, Keller H, Heim J
Novartis Pharma Inc., Basle, Switzerland.
Eur J Biochem. 1997 Oct 1;249(1):85-91. doi: 10.1111/j.1432-1033.1997.t01-1-00085.x.
bax is an apoptosis-inducing member of the bcl-2 multigene family. We have studied interactions of human Bax with itself, and with the apoptosis-preventing members Bcl-2 and Bcl-xL using a yeast two-hybrid system. Exhaustive Bax truncations were constructed and their interactions with full-length family members studied. Bax interacted similarly with itself as with the apoptosis-suppressing family members Bcl-2 and Bcl-xL in quantitative two-hybrid studies. A region of 41 amino acids covering the recently discovered BH3 domain of Bax was found to be necessary and sufficient for all interactions of Bax. Bax truncations containing BH3, but lacking BH1 and BH2 homology domains, interacted with the other family members markedly more strongly than full-length Bax, which may reflect conformational changes required for the interactions of full-length Bax. The minimum requirements for Bax homodimerization were found to be the BH3 domain from one Bax molecule and a region covering BH3 plus BH1 from another. We also studied the apoptosis-inducing activity of the Bax truncations upon microinjection of expression plasmids into rat fibroblasts. The BH3 region was required for the apoptosis-inducing activity of Bax, whereas BH1, BH2 and the N-terminus of Bax were dispensable.
Bax是bcl - 2多基因家族中诱导细胞凋亡的成员。我们利用酵母双杂交系统研究了人类Bax自身之间以及与抗凋亡成员Bcl - 2和Bcl - xL之间的相互作用。构建了Bax的详尽截短体，并研究了它们与全长家族成员的相互作用。在定量双杂交研究中，Bax与自身的相互作用方式与它和抗凋亡家族成员Bcl - 2及Bcl - xL的相互作用方式相似。发现一个覆盖Bax最近发现的BH3结构域的41个氨基酸区域对于Bax的所有相互作用都是必需且足够的。含有BH3但缺乏BH1和BH2同源结构域的Bax截短体与其他家族成员的相互作用明显比全长Bax更强，这可能反映了全长Bax相互作用所需的构象变化。发现Bax同源二聚化的最低要求是一个Bax分子的BH3结构域和另一个Bax分子覆盖BH3加BH1的区域。我们还通过将表达质粒显微注射到大鼠成纤维细胞中研究了Bax截短体的诱导细胞凋亡活性。BH3区域是Bax诱导细胞凋亡活性所必需的，而Bax的BH1、BH2和N末端则是可有可无的。
