P-glycoprotein function involves conformational transitions detectable by differential immunoreactivity
P-glycoprotein function involves conformational transitions detectable by differential immunoreactivity
复制标题
DOI：
10.1073/pnas.94.24.12908
复制
发表时间：
1997-11-25
影响因子：
11.1
通讯作者：
Roninson, IB
中科院分区：
文献类型：
--
作者：
Mechetner, EB;Schott, B;Roninson, IB
MDR1 p-糖蛋白（Pgp）是atp结合盒转运蛋白家族的一员，是一种跨膜atp酶外排泵，用于各种亲脂性化合物，包括许多抗癌药物，mAb UIC2，与Pgp的细胞外部分反应，抑制Pgp介导的外排。通过添加几种Pgp转运化合物或atp消耗剂，以及Pgp的两个核苷酸结合结构域（nbd）的突变失活，UIC2与Pgp的反应性增强。在Pgp转运底物存在或atp耗尽的细胞中，UIC2与两种NBD中突变的Pgp结合不受影响，而在单个NBD中突变的野生型Pgp和Pgp的反应性通过这些处理提高到双突变体的水平。这些结果表明，不同的Pgp构象与转运相关的ATP水解的不同阶段有关，并表明在瞬时构象中捕获是抗体介导的Pgp抑制的机制。
The MDR1 P-glycoprotein (Pgp), a member of the ATP-binding cassette family of transporters, is a transmembrane ATPase efflux pump for various lipophilic com pounds, including many anti-cancer drugs, mAb UIC2, reactive with the extracellular moiety of Pgp, inhibits Pgp-mediated efflux. UIC2 reactivity with Pgp was increased by the addition of several Pgp-transported compounds or ATP-depleting agents, and by mutational inactivation of both nucleotide-binding domains (NBDs) of Pgp. UIC2 binding to Pgp mutated in both NBDs was unaffected in the presence of Pgp transport substrates or in ATP-depleted cells, whereas the reactivities of the wild-type Pgp and Pgps mutated in a single NBD were increased by these treatments to the level of the double mutant. These results indicate the existence of different Pgp conformations associated with different stages of transport-associated ATP hydrolysis and suggest trapping in a transient conformation as a mechanism for antibody-mediated inhibition of Pgp.