多药耐药蛋白P-糖蛋白和MRP1的N端核苷酸结合结构域的三磷酸核苷酸酶活性。

Nucleotide triphosphatase activity of the N-terminal nucleotide-binding domains of the multidrug resistance proteins P-glycoprotein and MRP1.

作者信息

Wilkes Denise M, Wang Changsen, Aristimuño Patricia C, Castro Ariel F, Altenberg Guillermo A

机构信息

Membrane Protein Laboratory, Department of Physiology and Biophysics, The University of Texas Medical Branch Galveston, 301 University Boulevard, Galveston, TX 77555-0437, USA.

出版信息

Biochem Biophys Res Commun. 2002 Aug 16;296(2):388-94. doi: 10.1016/s0006-291x(02)00878-1.

DOI:10.1016/s0006-291x(02)00878-1

PMID:12163030

Abstract

The multidrug resistance proteins P-glycoprotein (Pgp) and MRP1 are drug-efflux pumps. In this study, we compared the nucleotide triphosphatase activities of the isolated N-terminal nucleotide binding domains (NBD1) of Pgp and MRP1, and explored the potential role of the phosphorylation target domain of Pgp on the regulation of Pgp NBD1 ATPase activity. We found that: (1) the NBD1s of Pgp and MRP1 have ATPase and GTPase activities, (2) the K(m)s of Pgp NBD1 for ATP and GTP hydrolysis are identical, while the K(m) of MRP1 NBD1 for ATP is lower than that for GTP, and (3) phosphorylation of MLD by PKA or PKC produces a marginal increase of V(max) for ATP hydrolysis, without affecting the affinity for ATP. These results show efficient GTP hydrolysis by the NBD1s of Pgp and MRP1, and a minor role of phosphorylation in the control of Pgp NBD1 ATPase activity.

摘要

多药耐药蛋白P-糖蛋白（Pgp）和多药耐药相关蛋白1（MRP1）是药物外排泵。在本研究中，我们比较了分离得到的Pgp和MRP1的N端核苷酸结合结构域（NBD1）的核苷酸三磷酸酶活性，并探讨了Pgp的磷酸化靶结构域在调节Pgp NBD1 ATP酶活性中的潜在作用。我们发现：（1）Pgp和MRP1的NBD1具有ATP酶和GTP酶活性；（2）Pgp NBD1对ATP和GTP水解的米氏常数（K(m)）相同，而MRP1 NBD1对ATP的K(m)低于对GTP的K(m)；（3）蛋白激酶A（PKA）或蛋白激酶C（PKC）对多药耐药相关蛋白（MLD）的磷酸化使ATP水解的最大反应速度（V(max)）略有增加，而不影响对ATP的亲和力。这些结果表明，Pgp和MRP1的NBD1能高效水解GTP，且磷酸化在控制Pgp NBD1 ATP酶活性中作用较小。