Cyt蛋白最初来源于苏云金杆菌，是一种杀虫蛋白。Cyt2Aa2蛋白的脂质结合依赖于脂双层的相位。本文通过原子力显微镜(AFM)研究了αD-β4环区保守的T144残基对流体脂质膜的脂质结合的重要性。通过POPC/DPPC、POPC/SM和DOPC/SM等脂质混合物系​​统监测了脂质膜流动性。AFM结果表明，T144A突变体无法结合到纯POP​​C双层。在POPC/Chol系统中，野生型和T144A突变型之间的形貌相似。在脂质混合物系统的POPC和DOPC区域观察到T144A突变体的小聚堆。此外，T144A突变体对人结肠癌细胞没有细胞毒作用。这些结果表明，将丙氨酸替换为苏氨酸144会阻碍Cyt2Aa2在液体脂质膜上的结合。这些观察结果为通过脂相选择修改Cyt2Aa2蛋白以作用于特定细胞提供了可能性。

Cyt proteins are insecticidal proteins originally from Bacillus thuringiensis. The lipid binding of the Cyt2Aa2 protein depends on the phase of the lipid bilayer. In this work, the importance of the conserved T144 residue in the αD-β4 loop for lipid binding on fluid lipid membranes was investigated via atomic force microscopy (AFM). Lipid membrane fluidity could be monitored for the following lipid mixture systems: POPC/DPPC, POPC/SM, and DOPC/SM. AFM results revealed that the T144A mutant was unable to bind to pure POPC bilayers. Similar topography between the wildtype and T144A mutant was seen for the POPC/Chol system. Small aggregates of T144A mutant were observed in the POPC and DOPC domains of the lipid mixture systems. In addition, the T144A mutant had no cytotoxic effect against human colon cancer cells. These results suggest that alanine replacement into threonine 144 hinders the binding of Cyt2Aa2 on liquid lipid membranes. These observations provide a possibility to modify the Cyt2Aa2 protein to specific cells via lipid phase selection.