ABCMdb

PMID: 8567633

Muller M, Bakos E, Welker E, Varadi A, Germann UA, Gottesman MM, Morse BS, Roninson IB, Sarkadi B
Altered drug-stimulated ATPase activity in mutants of the human multidrug resistance protein.
J Biol Chem. 1996 Jan 26;271(4):1877-83., 1996-01-26 [PubMed]

Sentences

No. Mutations Sentence Comment

5 ABCB1 p.Gly185Val ABCB1 p.Gly185Val In the MDR1 mutant containing a Gly185 to Val replacement we found no significant alteration in the maximum activity of the MDR1-ATPase or in its activation by verapamil and vinblastine, and this mutation did not modify the MgATP affinity or the 8-azido-ATP binding of the transporter either. However, the Gly185 to Val mutation significantly increased the stimulation of the MDR1-ATPase by colchicine and etoposide, while slightly decreasing its stimulation by vincristine. Login to comment 38 ABCB1 p.Gly185Val ABCB1 p.Lys1076Met ABCB1 p.Lys433Met In the present experiments we used site-directed mutagenesis to alter single amino acids of the human Pgp in the homology A consensus sequences in the NBDs of the NH2-terminal (Lys433 to Met) and/or COOH-terminal (Lys1076 to Met) halves, and applied the cDNA of the spontaneous Gly185 to Val substitution mutant. Login to comment 119 ABCB1 p.Gly185Val As shown above, in the case of the Gly185 to Val mutant we could not see a significant difference in the maximum level of verapamil-stimulated ATPase activity or in its MgATP concentration dependence. Login to comment 192 ABCB1 p.Gly185Val A single point mutation in human Pgp, a spontanous exchange of Gly to Val at position 185 (Choi et al., 1988), was reported to result in an increased relative resistance to colchicine and etoposide, while unchanged or slightly reduced resistance toward vinblastine and vincristine (Choi et al., 1988; Currier et al., 1992; Cardarelli et al., 1995). Login to comment 193 ABCB1 p.Gly185Val In this study we have reproduced the Gly185 to Val point mutation in the baculovirus-Sf9 expression system for MDR1. Login to comment 194 ABCB1 p.Gly185Val Our experiments showed no significant alteration in the maximum activity of the MDR1-ATPase or in its activation kinetics by verapamil and vinblastine, and this mutation did not modify the MgATP affinity or the 8-azido-ATP binding of the transporter either. However, the Gly185 to Val mutation significantly increased the stimulation of the MDR1-ATPase by colchicine and etoposide, while slightly decreasing its stimulation by vincristine. Login to comment 196 ABCB1 p.Gly185Val Moreover, the data indicating that the Gly185 to Val exchange, while increasing colchicine extrusion and colchicine stimulation of the MDR1-ATPase activity, reduces the binding of this drug to the MDR1 protein (Safa et al., 1990), may suggest that in the molecular mechanism of drug extrusion, ATP splitting is required for the dissociation of the drug from the transporter protein. Login to comment 198 ABCB1 p.Gly185Val While the present paper was under revision, a publication by U. S. Rao (1995) reported the expression and partial characterization of the Gly185 to Val MDR1 mutants in Sf9 cells. Login to comment