MOUSE MACROPHAGES SYNTHESIZE AND SECRETE A PROTEIN RESEMBLING APOLIPOPROTEIN-E
MOUSE MACROPHAGES SYNTHESIZE AND SECRETE A PROTEIN RESEMBLING APOLIPOPROTEIN-E
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DOI：
10.1073/pnas.78.12.7545
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发表时间：
1981-01-01
期刊：
影响因子：
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通讯作者：
GOLDSTEIN, JL
中科院分区：
文献类型：
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作者：
BASU, SK;BROWN, MS;GOLDSTEIN, JL
小鼠腹膜巨噬细胞的单层合成并分泌类似于载脂蛋白E（apoE）的蛋白质，载脂蛋白E是血浆脂蛋白的正常成分。通过用L[35 S]甲硫氨酸孵育巨噬细胞并分析分泌到培养基中的35 S标记蛋白来研究合成和分泌。35 S标记的类似apoE的蛋白质以< 1.215 μ g/ml的密度漂浮在超浓缩物中，表明它与脂质有关。通过NaDodSO 4 [十二烷基硫酸钠]/聚丙烯酰胺凝胶电泳，apoE样蛋白的MW为35，000，与从小鼠血浆极低密度脂蛋白获得的真实apoE的MW相同。其等电点为5.4，与小鼠apoE的等电点相同。二维等电聚焦/NaDodSO 4/聚丙烯酰胺凝胶电泳后，apoE样蛋白与真实的小鼠apoE共迁移，并可被抗大鼠apoE的单特异性抗体定量沉淀。当巨噬细胞通过与乙酰化低密度脂蛋白（乙酰-LDL）或β-LDL孵育而负载胆固醇时，apoE样蛋白的合成和分泌被刺激3至8倍。来自胆固醇喂养的兔子的迁移性极低密度脂蛋白。当将细胞与乙酰-LDL孵育时，apoE样蛋白质组成为：2%的由细胞合成的总35 S标记蛋白质和约10%的35 S标记蛋白分泌到培养基中。载脂蛋白E可能在从胆固醇负载的巨噬细胞分泌的胆固醇的血浆转运中起作用。
Monolayers of mouse peritoneal macrophages synthesize and secrete a protein that resembles apoprotein E (apoE), a normal constituent of plasma lipoproteins. Synthesis and secretion were studied by incubation of macrophages with L[35S]methionine and analysis of the 35S-labeled proteins secreted into the culture medium. The 35S-labeled protein resembling apoE floated in the ultracentrifuge at a density < 1.215 g/ml, indicating that it was associated with lipid. By NaDodSO4 [sodium dodecyl sulfate]/polyacrylamide gel electrophoresis the MW of the apoE-like protein was 35,000, identical to that of authentic apoE obtained from mouse plasma very low density lipoprotein. The isoelectric point of the apoE-like protein was 5.4 also the same as that of authentic mouse apoE. The apoE-like protein comigrated with authentic mouse apoE after 2-dimensional isoelectric focusing/NaDodSO4/polyacrylamide gel electrophoresis and it was quantitatively precipitated by a monospecific antibody directed against rat apoE. Synthesis and secretion of the apoE-like protein was stimulated 3- to 8-fold when the macrophages were loaded with cholesterol by incubation with either acetylated low density lipoprotein (acetyl-LDL) or .beta.-migrating very low density lipoprotein from cholesterol-fed rabbits. When the cells were incubated with acetyl-LDL, the apoE-like protein composed .apprx. 2% of the total 35S-labeled protein synthesized by the cells and .apprx. 10% of the total 35S-labeled protein secreted into the medium. apoE probably plays a role in the plasma transport of cholesterol excreted from cholesterol-loaded macrophages.