Amino acid substitutions in the first transmembrane domain (TM1) of P‐glycoprotein that alter substrate specificity

FEBS Letters

Taguchi, Yoshitomo¹  Komano, Tohru¹  Morishima, Masaki¹  Ueda, Kazumitsu¹ 

[1] Laboratory of Biochemistry, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-01, Japan

关键词: P-Glycoprotein;    Multidrug resistance;    Substrate specificity;    ABC transporter;    TM;    transmembrane domain;    CFTR;    cystic fibrosis transmembrane conductance regulator;    His;    histidine;    Ala;    alanine;    Gly;    glycine;    Ile;    isoleucine;    Arg;    arginine;    Vbl;    vinblastine;    Col;    colchicine;    Adr;    adriamycin;   

DOI  :  10.1016/S0014-5793(97)00899-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Recently, we showed that the amino acid at position 61 in TM1 of human P-glycoprotein is important in deciding the substrate specificity of this protein. In this work, we investigated whether the amino acids other than His⁶¹ in TM1 of P-glycoprotein are also essential in the function of this protein. Nine amino acids residues, from Ala⁵⁷ to Leu⁶⁵ in TM1, were independently substituted to Arg, and analyzed the drug resistance of cells stably expressing each of these mutant P-glycoproteins. The mutant P-glycoproteins Ile⁶⁰→Arg, His⁶¹→Arg, Ala⁶³→Arg, Gly⁶⁴→Arg, and Leu⁶⁵→Arg were normally processed and expressed in the plasma membrane. Substrate specificities of mutant P-glycoproteins Gly⁶⁴→Arg and Leu⁶⁵→Arg were quite different from that of the wild type, and similar to that of the His⁶¹→Arg mutant, while the Ile⁶⁰→Arg and Ala⁶³→Arg mutant P-glycoproteins showed similar substrate specificities to that of the wild-type P-glycoprotein, suggesting that not only the amino acid residue at position 61 but also those at position 64 and 65 are also important in deciding the substrate specificity of P-glycoprotein. These three amino acids His⁶¹, Gly⁶⁴, and Leu⁶⁵ would form a compact region on an α-helix arrangement of TM1. These results suggest that a region consisting of His⁶¹, Gly⁶⁴, and Leu⁶⁵ in TM1 would participate in the formation of the recognition site for substrates of P-glycoprotein.

【 授权许可】

Unknown