Kasper A M, Helmkamp G M
Biochim Biophys Acta. 1981 Apr 23;664(1):22-32. doi: 10.1016/0005-2760(81)90025-4.
Bovine brain phospholipid exchange protein catalyzes the transfer of phosphatidylinositol and phosphatidylcholine between two populations of single bilayer vesicles. The inclusion of lactosylceramide in one of the vesicle populations and the ability to precipitate those vesicles in the presence of Ricinus communis agglutinin assures the quantitative separation of donor and acceptor vesicles following incubation with exchange protein. When both vesicle populations contain phosphatidylinositol and phosphatidylcholine and transfers are monitored in both directions, the flux of phosphatidylinositol (or phosphatidylcholine) in the forward direction equals that in the reverse. When one of the vesicle populations initially lacks phosphatidylinositol, a net unidirectional transfer of that phospholipid occurs. Concurrently, a compensatory flux of phosphatidylcholine takes place in the opposite direction, such that the bidirectional fluxes of total phospholipid are equal. A net transfer of phosphatidylcholine is also demonstrated. A mechanism of true molecular exchange between vesicles, rather than net transfer, is proposed for the bovine brain phospholipid exchange protein.
牛脑磷脂交换蛋白催化磷脂酰肌醇和磷脂酰胆碱在两个单层囊泡群体之间的转移。在其中一个囊泡群体中加入乳糖神经酰胺，并能够在蓖麻凝集素存在的情况下沉淀这些囊泡，这确保了在与交换蛋白孵育后供体囊泡和受体囊泡的定量分离。当两个囊泡群体都含有磷脂酰肌醇和磷脂酰胆碱，并且在两个方向上监测转移时，磷脂酰肌醇（或磷脂酰胆碱）正向转移的通量等于反向转移的通量。当其中一个囊泡群体最初缺乏磷脂酰肌醇时，会发生该磷脂的净单向转移。同时，磷脂酰胆碱会在相反方向发生补偿性通量，使得总磷脂的双向通量相等。还证明了磷脂酰胆碱的净转移。对于牛脑磷脂交换蛋白，提出了一种囊泡之间真正分子交换而非净转移的机制。
