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载脂蛋白AI促进胆固醇从外周细胞流出，在高密度脂蛋白对胆固醇的逆向运输中起关键作用。为探讨载脂蛋白AI介导胆固醇流出功能的结构特征，观察了天然存在的氨基酸置换：载脂蛋白AI结构中第156位上的缬氨酸由谷氨酸置换，和氨基酸缺失：第235位上的谷氨酸缺失对载脂蛋白AI促胆固醇从鼠腹腔巨噬细胞流出能力的影响。以体外培养的鼠腹腔巨噬细胞为对象，用氚标油酸酯标记的乙酰化低密度脂蛋白作泡沫细胞诱导物，巨噬细胞与载脂蛋白AI孵育一段时间后．测定由细胞释放入培养基中的3H标记胆固醇量。结果发现载脂蛋白AI结构中第156位的缬氨酸由谷氨酸置换不影响载脂蛋白AI的促细胞胆固醇流出能力，而第235位上的谷氨酸缺失可使胆固醇流出能力降低50％，差异有极显著性意义（P＜0．01）。此结果提示，载脂蛋白AI的C末端残基第235位谷氨酸对胆固醇流出功能起重要作用。
Apolipoprotein AI promotes the efflux of cholesterol from peripheral cells and plays a key role in the reverse transport of cholesterol by high-density lipoproteins. To explore the structural features of apolipoprotein AI-mediated cholesterol efflux function, naturally occurring amino acid substitutions were observed: valine at position 156 in apolipoprotein AI structure is replaced by glutamic acid, and amino acid deletions: position 235 On the ability of apolipoprotein AI-induced cholesterol efflux from murine peritoneal macrophages. Mouse peritoneal macrophages cultured in vitro were used as foam cell inducer with tritiated oleate labeled acetylated low density lipoprotein and macrophages incubated with apolipoprotein AI for a period of time. The amount of 3H-labeled cholesterol released into the medium by the cells was measured. As a result, it was found that the replacement of valine at position 156 in the apolipoprotein AI structure by glutamate did not affect the ability of apolipoprotein AI to promote the efflux of cellular cholesterol while the loss of glutamate at position 235 reduced the efflux of cholesterol by 50 %, The difference was extremely significant (P <0.01). This result suggests that glutamate at C-terminal of apolipoprotein AI plays an important role in cholesterol efflux function.