Sorting of lipids and transmembrane peptides between detergent-soluble bilayers and detergent-resistant rafts
Sorting of lipids and transmembrane peptides between detergent-soluble bilayers and detergent-resistant rafts
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DOI：
10.1016/s0006-3495(03)74595-0
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发表时间：
2003-09-01
影响因子：
3.4
通讯作者：
Simon, SA
中科院分区：
文献类型：
--
作者：
McIntosh, TJ;Vidal, A;Simon, SA
特定的蛋白质和脂质被隔离在细胞膜上称为筏的区域。由于鞘磷脂（SM）和胆固醇含量高，筏式双层比非筏式双层更厚，至少在4度以上，可以抵抗Triton X-100提取。由于跨双层结构域和厚双层碳氢化合物区之间的“疏水匹配”，筏集中了具有长跨双层结构域的蛋白质。然而，由于SM：胆固醇双分子层的面积可压缩性和弯曲模量比非筏体双分子层大，因此将蛋白质或肽分割成筏体应该有能量成本。为了确定筏板厚度和机械性能对肽分选的影响，我们将两种跨双层肽（P-23、P-29）加入到SM、二油酰磷脂酰胆碱和胆固醇组成的双层中，分离了洗涤剂可溶性膜（DSMs）和洗涤剂抗性膜（DRMs），并测量了它们的肽和脂质组成。P-23和P-29被设计成具有与DSMs和DRMs的碳氢化合物厚度相匹配的跨双层结构域。在4°c和37°c时，DSMs富集于二油基磷脂酰胆碱，DRMs富集于SM和胆固醇。在这两种温度下，P-23和P-29都优先定位于DSMs，证明了双层力学性能相对于疏水失配的重要性。然而，在37℃时，P-29明显多于P-23，这表明疏水匹配在生理温度下的肽分选中发挥了作用。这些实验表明，通过洗涤剂萃取测量的肽分选是温度依赖的，双层机械性能和疏水匹配都会影响DSMs和DRMs之间的肽分布。
Specific proteins and lipids sequester to regions of cell membranes called rafts. Due to their high content of sphingomyelin (SM) and cholesterol, raft bilayers are thicker than nonraft bilayers and, at least at 4degreesC, are resistant to Triton X-100 extraction. It has been postulated that rafts concentrate proteins with long transbilayer domains because of "hydrophobic matching'' between the transbilayer domain and the thick bilayer hydrocarbon region. However, because the area compressibility and bending moduli of SM:cholesterol bilayers are larger than that of nonraft bilayers, there should be an energy cost to partition proteins or peptides into rafts. To determine the effects on peptide sorting of raft thickness and mechanical properties, we incorporated two transbilayer peptides (P-23, P-29) into bilayers composed of SM, dioleoylphosphatidylcholine, and cholesterol, separated detergent-soluble membranes (DSMs) from detergent-resistant membranes (DRMs), and measured their peptide and lipid compositions. P-23 and P-29 were designed to have transbilayer domains that matched the hydrocarbon thicknesses of DSMs and DRMs, respectively. At both 4degreesC and 37degreesC DSMs were enriched in dioleoylphosphatidylcholine and DRMs were enriched in SM and cholesterol. At both temperatures both P-23 and P-29 preferentially localized to DSMs, demonstrating the importance of bilayer mechanical properties relative to hydrophobic mismatch. However, at 37degreesC significantly more P-29 than P-23 was located in DRMs, implying that hydrophobic matching played a role in peptide sorting at physiological temperature. These experiments demonstrate that the sorting of peptides as measured by detergent extraction is temperature-dependent and both bilayer mechanical properties and hydrophobic matching impact peptide distribution between DSMs and DRMs.