Open AccessLysine 268 adjacent to transmembrane helix 5 of hamster P‐glycoprotein is the major photobinding site of iodomycin in CHO B30 cells
Author(s) -
Demmer Annette,
Thole Hubert,
Raida Manfred,
Tümmler Burkhard
Publication year - 2021
Publication title -
febs open bio
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.718
H-Index - 31
ISSN - 2211-5463
DOI - 10.1002/2211-5463.13112
Subject(s) - chinese hamster ovary cell , chemistry , peptide , biochemistry , lysine , hamster , transmembrane protein , transmembrane domain , vesicle , binding site , cyanogen bromide , glycoprotein , peptide sequence , membrane , biophysics , microbiology and biotechnology , amino acid , biology , receptor , gene
P‐glycoprotein (Pgp) detoxifies cells by exporting hundreds of chemically dissimilar hydrophobic and amphipathic compounds and is implicated in multidrug resistance (MDR) in the treatment of cancers. Photoaffinity labeling of plasma membrane vesicles of MDR CHO B30 cells with the anthracycline [ 125 I]‐iodomycin, subsequent sequential cleavage with BNPS‐skatol and endoproteinase Lys‐C, and the Edman sequencing of the purified photoaffinity‐labeled peptide identified the lysine residue at position 268 in the hamster Pgp primary sequence as the major photobinding site of iodomycin in CHO B30 cells. Lysine 268 is located adjacent to the cytosolic terminus of transmembrane 5. According to thermodynamic and kinetic analyses, this location should present the equilibrium binding site of ATP‐free Pgp for daunomycin and iodomycin in B30 cells.