LIPID-PROTEIN INTERACTIONS IN ADP-ATP CARRIER EGG PHOSPHATIDYLCHOLINE RECOMBINANTS STUDIED BY SPIN-LABEL ESR SPECTROSCOPY
LIPID-PROTEIN INTERACTIONS IN ADP-ATP CARRIER EGG PHOSPHATIDYLCHOLINE RECOMBINANTS STUDIED BY SPIN-LABEL ESR SPECTROSCOPY
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DOI：
10.1021/bi00499a013
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发表时间：
1990-11-27
期刊：
影响因子：
2.9
通讯作者：
MARSH, D
中科院分区：
文献类型：
--
作者：
HORVATH, LI;DREES, M;MARSH, D
根据线粒体ADP-ATP载体与卵磷脂酰胆碱重组络合物中自旋标记脂类的电子自旋共振光谱，确定了脂-蛋白相互作用的化学计量比和特异性，以及蛋白质界面的脂交换速率。除了心磷脂和磷脂酸，被研究的脂类被发现在蛋白质二聚体的膜内表面竞争大约50个位置。对于这种大小的蛋白质来说，第一壳类脂部位的数量是异常多的。该蛋白质的特异性为硬脂酸.apprxeq。磷脂酸.apprxeq.心磷脂和GT；磷脂酰丝氨酸和GT；磷脂酰甘油。磷脂酰胆碱的最大结合常数约为4。阴离子脂类化合物的选择性随离子强度的增加而部分增加，但对心磷脂和磷脂酸的选择性比对硬脂酸的选择性小。只有在磷脂酰丝氨酸的情况下，在高离子强度下选择性降低到接近于磷脂酰胆碱的水平。蛋白质表面脂交换的关闭速率与脂/蛋白比无关，并与不同的脂选择系数成倒数相关，在5倍之间变化。S~(-1)为低离子强度硬脂酸的2倍。磷脂酰胆碱和磷脂酰甘油为107S-1。与观察到的选择性相比，心磷脂的脱落率异常低，这表明心磷脂存在一种特殊的部位群(约占总数的30%)，在这种情况下，交换率非常低。这些结果参考了早期对这种疏水性膜蛋白的观察结果进行了讨论。
The stoichiometry and specificity of lipid-protein interaction, as well as the lipid exchange rates at the protein interface, have been determined from the electron spin resonance spectra of spin-labeled lipids in reconstituted complexes of the mitochondrial ADP-ATP carrier with egg phosphatidylcholine. With the exception of cardiolipin and phosphatidic acid, the lipids studied are found to compete for approximately 50 sites at the intramembranous surface of the protein dimer. This number of first-shell lipid sites is unusually large for a protein of this size. The specificity for the protein is in the order stearic acid .apprxeq. phosphatidic acid .apprxeq. cardiolipin > phosphatidylserine > phosphatidylglycerol .apprxeq. phosphatidylcholine, with the maximum association constant relative to phosphatidylcholine being approximately 4. The selectivity for anionic lpids was partially screened with increasing ionic strength, but to a lesser extent for cadiolipin and phosphatidic acid than for stearic acid. Only in the case of phosphatidylserine was the selectivity reduced at high ionic strength to a level close to that for phosphatidylcholine. The off rates for lipid exchange at the protein surface were independent of lipid/protein ratio and correlated in a reciprocal fashion with the different lipid selectivities, varying from 5 .times. 106 s-1 for stearic acid at low ionic strength to 2 .times. 107 s-1 for phosphatidylcholine and phosphatidylglycerol. The off rates for cardiolipin were unusually low in comparison with the observed selectivity, and indicated the existence of a special population of sites (ca. 30% of the total) for cardiolipin, at which the exchange rate was very low. These results are discussed with reference to earlier observations on this hydrophobic membrane protein.