ABCB1 p.Met69Arg

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PMID: 18596043 [PubMed] Loo TW et al: "Arginines in the first transmembrane segment promote maturation of a P-glycoprotein processing mutant by hydrogen bond interactions with tyrosines in transmembrane segment 11."
No. Sentence Comment
117 Introduction of arginines at other positions at the extracellular end of TM1 had little effect (10-20% mature P-gp in mutants L67R, M69R, and L70R) or reduced the level of mature product to less than 10% of total P-gp (mutants P66R and F72R).
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ABCB1 p.Met69Arg 18596043:117:132
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142 Therefore, mutants showing reduced (T55R/G251V) or similar maturation efficiencies (H61R/G251V, M69R/G251V) to the G251V parent were expressed in the presence of 5 ␮M cyclosporin A, 30 ␮M verapamil, 5 ␮M vinblastine, or 30 ␮M rhodamine B.
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ABCB1 p.Met69Arg 18596043:142:96
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147 By contrast, all drugs except verapamil rescued mutant M69R/G251V (Fig. 5).
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ABCB1 p.Met69Arg 18596043:147:55
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163 HEK 293 cells expressing mutants G251V, T55R/G251V, H61R/G251V, or M69R/G251V were treated with no drug (None), 5 ␮M cyclosporin A (Cyclo), 30 ␮M verapamil (Ver), 5 ␮M vinblastine (Vin), or 30 ␮M rhodamine B (Rhod) for 24 h. Whole cell extracts were then subjected to immunoblot analysis.
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ABCB1 p.Met69Arg 18596043:163:67
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165 TABLE 1 Effects of drug substrates on the maturation of TM1 arginine mutants containing the G251V mutation Mutation (G251V ؉) No drug Cyclosporin A Verapamil Vinblastine Rhodamine None - 111a,c 111 111 11 V52R -a,b 111 111 111 11 V53R 2 - - - - G64R 2 - - - - T55R 2 - - - - L56R 2 - - - - A57R 2 - - - - A58R 2 - - - - I59R 2 - - - - I60R 2 - - - - H61R - 111 1 1 1 G62R 2 - - - - A63R 2 - - - - G64R 1 111 1 1 11 L65R 11 111 11 11 11 P66R 2 1 - - - L67R - 111 111 111 11 M68R 111 111 111 111 111 M69R - 111 - 11 111 L70R - 111 111 111 11 V71R 1 111 111 111 11 F72R 2 1 1 1 1 a Change in the amount of mature (170 kDa) protein in the presence of drug substrate relative to that in the absence of drug substrate.
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ABCB1 p.Met69Arg 18596043:165:504
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276 Mutants H61R/G251V or M69R/G251V showed little drug rescue with verapamil (Fig. 5), and mutants G64R and M68R in a wild-type background showed reductions in apparent affinity for verapamil in ATPase assays (Fig. 7).
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ABCB1 p.Met69Arg 18596043:276:22
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PMID: 26507655 [PubMed] Loo TW et al: "Mapping the Binding Site of the Inhibitor Tariquidar That Stabilizes the First Transmembrane Domain of P-glycoprotein."
No. Sentence Comment
156 For example, we showed that an M69R mutation specifically blocked rescue of a P-gp G251V processing mutant with verapamil but not rescue with cyclosporine A, vinblastine, or rhodamine B (43).
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ABCB1 p.Met69Arg 26507655:156:31
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175 In the N-terminal TMD1 domain, the largest number of arginine mutations predicted to line the drug-binding pocket that inhibited tariquidar rescue were located in TM1 (H61R, G64R, L65R, M68R, M69R, and F72R) and TM5 (F303R, I306R, Y307R, S309R, and Y310R) (Fig. 4, A and E).
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ABCB1 p.Met69Arg 26507655:175:192
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193 It was found that 16 of the 28 mutants resembled the G251V/I868R mutant as expression in the presence of 5 òe;M cyclosporine A yielded mature P-gp as the major product in TM1 (H61R, G64R, L65R, M68R, and M69R), TM5 (F303R, I306R, and S309R), TM7 (Q725R and F728R), TM10 (I868R and G872R), TM11 (F942R, T945R, and Q946R), and TM12 (V982R) (Fig. 7).
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ABCB1 p.Met69Arg 26507655:193:208
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212 Seventeen of the 30 G251V/arginine mutants (M68R, M69R, and F72R in TM1; I306R, Y307R, S309R, and Y310R in TM5; F336R in TM6; F728R and F732R in TM7; I868R and G872R in TM10; F942R, T945R, M949R, and S952R in TM11; and V982R in TM12) that could not be rescued with tariquidar showed little or no stimulation of ATPase activity with tariquidar (Fig. 8A).
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ABCB1 p.Met69Arg 26507655:212:50
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