Induction mechanism of AIF-related cell death

为了阐明AIF的确切膜结合方式，我们收缩了过表达小鼠AIF、线粒体型AIF （delta 1-53）和切割型AIF （delta 1-102）的重组大肠杆菌菌株。我们发现，当制备缓冲液的离子强度(I)与生理条件（I = 150 mM）相同时，80%以上的线粒体型AIF与膜相关。而在高条件下（I = 300 mM），大部分酶（95%）从膜上解离。值得注意的是，劈裂型AIF在低I时部分与膜结合（约50%），并随着I的增加而解离。这些结果表明，AIF的n端区域（残基67-85）参与了膜结合，但不是绝对必要的，AIF与膜的结合方式可能是离子键。

To elucidate exact membrane-binding manner of AIF, we contracted recombinant E. coli strains which overexpressed mouse AIFs, mitochondria-type AIF (delta 1-53) or cleaved-type AIF (delta 1-102). We found that more than 80% of mitochondria-type AIF was associated to the membrane when the ionic strength (I) of preparation buffer was the same as a physiological conditions (I = 150 mM). While, at high conditions (I = 300 mM), most enzyme (95%) was dissociated from the membrane. It is noteworthy that cleaved-type AIF partly associated to the membrane (about 50%) at low I, and was also dissociated by increasing I. These results suggest that the N-terminal region (residues 67-85) of AIF is involved in the membrane-binding but is not absolutely necessary and the binding manner of AIF to the membrane may be an ion bond.