Conformation-dependent interaction of alpha-lactalbumin with model and biological membranes: a spin-label ESR study.
Conformation-dependent interaction of alpha-lactalbumin with model and biological membranes: a spin-label ESR study.
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α-乳清蛋白与模型和生物膜的构象依赖性相互作用：自旋标记 ESR 研究。
DOI：
10.1023/b:jopc.0000016263.50484.e1
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Berliner,LawrenceJ
中科院分区：
文献类型：
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作者：
Chaudhuri,Dipankar;Narayan,Mahesh;Berliner,LawrenceJ
α-乳蛋白(α-LA)被生物合成并储存在光滑内质网(ER)中，当催乳素刺激乳糖的生物合成和分泌时，它被转移到高尔基体的管腔。由于这两种环境都是由膜组成的，因此研究α-LA与相关模型膜和生物膜的相互作用是有意义的。利用电子自旋标记脂肪酸类似物5-十二烷基硬脂酸，我们发现证据表明，“酸休克”的熔球(MG)α-LA插入卵磷脂或磷脂酰丝氨酸(PS)多层囊泡。在∼-LA-卵磷脂样品中观察到额外的α3 G固定化，而不是仅在脂类中观察到。对于PS，增加的固定化几乎是6G，反映了在pH为2.4时，带正电荷的蛋白质与带负电荷的头基之间的强烈静电相互作用所引起的增强效应。这也反映在PS：α-LA相变的展宽上。此外，我们还证明了脱脂形式的α-LA也表现出与模型脂膜和天然脂膜相似的插入特性。加入钙后，脱氧核糖体以钙结合蛋白的形式从膜上释放出来。
α-Lactalbumin (α-LA) is biosynthesized and stored at the smooth endoplasmic reticulum (ER), then transferred to the Golgi lumen when prolactin stimulation of lactose biosynthesis and secretion takes place. Because both environments are composed of membranes, it was of interest to examine the interactions of α-LA with relevant model and biological membranes. Using the ESR spin-labeled fatty acid analog 5-doxyl stearic acid, we found evidence reflecting the insertion of “acid-shocked” molten globule (MG) α-LA into lecithin or phosphatidylserine (PS) multi-lamellar vesicles. An additional ∼3 G immobilization was observed in the α-LA-lecithin sample versus the lipid alone. With PS, the increased immobilization was almost 6 G, reflecting an enhanced effect caused by strong electrostatic interactions between the positively charged protein with the negatively charged headgroup at pH 2.4. This was also reflected in the broadening of the PS:α-LA phase transition. Additionally, we have demonstrated that α-LA in its apo-form also shows similar insertion characteristics with both model and natural lipid membranes. Upon addition of calcium, the apo-form is released from the membrane as the Ca2+-bound protein.