PHOSPHOLIPID BINDING OF ANNEXIN-V - EFFECTS OF CALCIUM AND MEMBRANE PHOSPHATIDYLSERINE CONTENT
PHOSPHOLIPID BINDING OF ANNEXIN-V - EFFECTS OF CALCIUM AND MEMBRANE PHOSPHATIDYLSERINE CONTENT
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DOI：
10.1016/0003-9861(92)90111-9
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发表时间：
1992-10-01
影响因子：
3.9
通讯作者：
GIBSON, D
中科院分区：
文献类型：
--
作者：
TAIT, JF;GIBSON, D
我们研究了荧光素标记的膜联蛋白V（胎盘抗凝蛋白I）在0.15离子强度下与单层磷脂小泡的结合与钙浓度和膜磷脂酰丝氨酸（PS）含量的关系。当膜中PS的摩尔百分比从10%增加到50%时，在1.2 mmCaCl2下测量的结合化学计量从1100 mol磷脂/mol膜联蛋白V双曲线下降到84 mol/mol的极限值。在PS含量相同的范围内，kd保持在0.036±0.011 nm近似恒定。当钙浓度从0.4 mm增加到10 mm时，观察到含有10%或20% PS的囊泡的化学计量学也出现了类似的双曲线下降。因此，膜结合位点的密度强烈依赖于膜PS含量和钙浓度。钙对膜联蛋白v膜结合的影响被认为是由于形成磷脂-钙复合物，蛋白质与之结合，而不是钙对蛋白质磷脂亲和力的变构作用。
We studied the binding of fluorescein-labeled annexin V (placental anticoagulant protein I) to small unilamellar phospholipid vesicles at 0.15mionic strength as a function of calcium concentration and membrane phosphatidylserine (PS) content. As the mole percentage of PS in the membrane increased from 10 to 50%, the stoichiometry of binding decreased hyperbolically from 1100 mol phospholipid/mol annexin V to a limiting value of 84 mol/mol for measurements made at 1.2 mmCaCl2. Over the same range of PS content,Kdremained approximately constant at 0.036 ± 0.011 nm. A similar hyperbolic decrease in stoichiometry was observed with vesicles containing 10 or 20% PS when the calcium concentration was increased from 0.4 to 10 mm. Thus, the density of membrane binding sites is strongly dependent on the membrane PS content and calcium concentration. The effect of calcium on annexin V-membrane binding is proposed to be due to the formation of phospholipid-calcium complexes, to which the protein binds, rather than to an allosteric effect of calcium on proteinphospholipid affinity.