Relationship between Amphipathic β Structures in the β1 Domain of Apolipoprotein B and the Properties of the Secreted Lipoprotein Particles in McA-RH7777 Cells.
Relationship between Amphipathic β Structures in the β1 Domain of Apolipoprotein B and the Properties of the Secreted Lipoprotein Particles in McA-RH7777 Cells.
复制标题
载脂蛋白 B 的 β1 结构域中的两亲性 β 结构与 McA-RH7777 细胞中分泌的脂蛋白颗粒的特性之间的关系。
DOI：
10.1021/acs.biochem.6b01174
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发表时间：
2017
期刊：
影响因子：
2.9
通讯作者：
Dashti,Nassrin
中科院分区：
文献类型：
--
作者：
Manchekar,Medha;Kapil,Richa;Sun,Zhihuan;Segrest,JereP;Dashti,Nassrin
我们之前的研究表明，人类载脂蛋白（apo） B-100的前1000个氨基酸残基（βα1结构域），称为apoB:1000，是启动脂蛋白组装和形成单分散稳定的富含磷脂（PL）颗粒所必需的。本研究的目的是(a)评估在apoB-100的β1结构域的700个n端残基中连续包含两性β链对载脂蛋白ob截断物性质的影响，(b)鉴定β1结构域中形成微粒体甘油三酯转移蛋白（MTP）依赖的富含三酰甘油（TAG）的载脂蛋白ob颗粒所必需的亚结构域。McA-RH7777细胞稳定转化子分泌的颗粒的表征表明：(1)在β1结构域的200个n端残基中存在两亲性β链，导致apoB截断（apoB:1050至apoB:1200）作为脂化和贫脂颗粒分泌。(2) β1结构域300-700残基的包合导致apoB:1300、apoB:1400、apoB:1500和apoB:1700主要以脂化颗粒的形式分泌。(3)含有1050 ~ 1500残基的颗粒均富含PL。(4)含有apoB:1700的颗粒的载脂能力和TAG含量显著增加。(5) MTP抑制剂BMS-197636仅能显著降低apoB:1700的分泌水平。这些结果表明，apoB:1700标志着富含tag的颗粒形成的阈值，并支持了MTP在颗粒从富含pl到富含tag过渡阶段参与apoB组装和分泌的概念。
Our previous studies demonstrated that the first 1000 amino acid residues (the βα1domain) of human apolipoprotein (apo) B-100, termed apoB:1000, are required for the initiation of lipoprotein assembly and the formation of a monodisperse stable phospholipid (PL)-rich particle. The objectives of this study were (a) to assess the effects on the properties of apoB truncates undergoing sequential inclusion of the amphipathic β strands in the 700 N-terminal residues of the β1domain of apoB-100 and (b) to identify the subdomain in the β1domain that is required for the formation of a microsomal triglyceride transfer protein (MTP)-dependent triacylglycerol (TAG)-rich apoB-containing particle. Characterization of particles secreted by stable transformants of McA-RH7777 cells demonstrated the following. (1) The presence of amphipathic β strands in the 200 N-terminal residues of the β1domain resulted in the secretion of apoB truncates (apoB:1050 to apoB:1200) as both lipidated and lipid-poor particles. (2) Inclusion of residues 300–700 of the β1domain led to the secretion of apoB:1300, apoB:1400, apoB:1500, and apoB:1700 predominantly as lipidated particles. (3) Particles containing residues 1050–1500 were all rich in PL. (4) There was a marked increase in the lipid loading capacity and TAG content of apoB:1700-containing particles. (5) Only the level of secretion of apoB:1700 was markedly diminished by MTP inhibitor BMS-197636. These results suggest that apoB:1700 marks the threshold for the formation of a TAG-rich particle and support the concept that MTP participates in apoB assembly and secretion at the stage where particles undergo a transition from PL-rich to TAG-rich.