EFFECT OF BOVINE BASIC-PROTEIN CHARGE MICROHETEROGENEITY ON PROTEIN-INDUCED AGGREGATION OF UNILAMELLAR VESICLES CONTAINING A MIXTURE OF ACIDIC AND NEUTRAL PHOSPHOLIPIDS
EFFECT OF BOVINE BASIC-PROTEIN CHARGE MICROHETEROGENEITY ON PROTEIN-INDUCED AGGREGATION OF UNILAMELLAR VESICLES CONTAINING A MIXTURE OF ACIDIC AND NEUTRAL PHOSPHOLIPIDS
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DOI：
10.1021/bi00329a016
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发表时间：
1985-01-01
期刊：
影响因子：
2.9
通讯作者：
MOSCARELLO, MA
中科院分区：
文献类型：
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作者：
CHEIFETZ, S;MOSCARELLO, MA
分离了髓鞘碱性蛋白微异构体中的两种电荷异构体（组分1和组分2），研究了它们聚集由混合磷脂组成的囊泡的能力。组分1是阳离子性最强的微异构体，与组分2相比，组分2以较低的蛋白质浓度聚集了含有7.8 mol%磷脂酰丝氨酸（PS）的磷脂酰胆碱（PC）囊泡，与组分1相差1个净正电荷。体外用兔肌蛋白激酶磷酸化修饰组分1和2，可降低两组分聚集囊泡的能力。磷酸化程度越大，同分异构体诱导聚集的效果越差。通过去除2个c端精氨酸基残基来降低组分1或组分2的电荷也降低了同分异构体诱导聚集的能力。无论是体内产生的还是体外产生的电荷微异质性，都显著影响了这些微异质体聚集含有7.8 mol% PS的PC囊泡的能力。由于蛋白质电荷的微小差异对囊泡聚集有显著影响，电荷微异质性可能在正常髓磷脂的结构和功能中起着重要的动态作用。
Two of the charge isomers (components 1 and 2) normally found as microheteromers of myelin basic protein were isolated, and their abilities to aggregate vesicles consisting of mixed phospholipids were studied. Component 1 (the most cationic of the microheteromers) aggregated phosphatidylcholine (PC) vesicles containing 7.8 mol% phosphatidylserine (PS) more rapidly and at lower protein concentrations than component 2, which differs from component 1 by 1 net positive charge. Modification of components 1 and 2 in vitro by phosphorylation with rabbit muscle protein kinase decreased the ability of both components to aggregate vesicles. The greater the extent of phosphorylation, the less effective were the isomers at inducing aggregation. Decreasing the charge of either component 1 or component 2 by removal of the 2 C-terminal arginyl residues also decreased the ability of the isomers to induce aggregation. Charge microheterogeneity, whether arising in vivo or generated in vitro, markedly affected the ability of these microheteromers to aggregate PC vesicles containing 7.8 mol% PS. Because a small difference in the charge of the protein had a marked effect on vesicle aggregation, charge microheterogeneity may play an important and dynamic role in the structure and function of normal myelin.