ABCMdb

ABCB1 p.Phe978Arg

Predicted by SNAP2:	A: D (66%), C: N (57%), D: D (91%), E: D (85%), G: D (80%), H: D (80%), I: N (78%), K: D (85%), L: N (66%), M: N (53%), N: D (75%), P: D (91%), Q: D (71%), R: D (85%), S: N (53%), T: D (71%), V: N (61%), W: D (85%), Y: D (66%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, G: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: D, T: D, V: D, W: D, Y: N,

[switch to compact view]
Comments [show]

None has been submitted yet.

Publications
[hide] Mapping the Binding Site of the Inhibitor Tariquid... J Biol Chem. 2015 Dec 4;290(49):29389-401. doi: 10.1074/jbc.M115.695171. Epub 2015 Oct 26. Loo TW, Clarke DM
Mapping the Binding Site of the Inhibitor Tariquidar That Stabilizes the First Transmembrane Domain of P-glycoprotein.
J Biol Chem. 2015 Dec 4;290(49):29389-401. doi: 10.1074/jbc.M115.695171. Epub 2015 Oct 26., [PMID:26507655]

Abstract [show]
ABC (ATP-binding cassette) transporters are clinically important because drug pumps like P-glycoprotein (P-gp, ABCB1) confer multidrug resistance and mutant ABC proteins are responsible for many protein-folding diseases such as cystic fibrosis. Identification of the tariquidar-binding site has been the subject of intensive molecular modeling studies because it is the most potent inhibitor and corrector of P-gp. Tariquidar is a unique P-gp inhibitor because it locks the pump in a conformation that blocks drug efflux but activates ATPase activity. In silico docking studies have identified several potential tariquidar-binding sites. Here, we show through cross-linking studies that tariquidar most likely binds to sites within the transmembrane (TM) segments located in one wing or at the interface between the two wings (12 TM segments form 2 divergent wings). We then introduced arginine residues at all positions in the 12 TM segments (223 mutants) of P-gp. The rationale was that a charged residue in the drug-binding pocket would disrupt hydrophobic interaction with tariquidar and inhibit its ability to rescue processing mutants or stimulate ATPase activity. Arginines introduced at 30 positions significantly inhibited tariquidar rescue of a processing mutant and activation of ATPase activity. The results suggest that tariquidar binds to a site within the drug-binding pocket at the interface between the TM segments of both structural wings. Tariquidar differed from other drug substrates, however, as it stabilized the first TM domain. Stabilization of the first TM domain appears to be a key mechanism for high efficiency rescue of ABC processing mutants that cause disease.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
188 These were in TM7 (Q725R, F728R, and F732R) (Fig. 6A), TM10 (V865R, I868R, and G872R) (Fig. 6D), TM11 (F942R, T945R, Q946R, M949R, Y950R, and Y953R) (Fig. 6E), and TM12 (L975R, F978R, and V982R) (Fig. 6F). Login to comment
194 The other 12 mutants in TM1 (F72R), TM5 (Y307R and Y310R), TM6 (F336R and F343R), TM7 (F732R), TM10 (V865R), TM11 (M949R, Y950R, S952R, and Y953R), and TM12 (L975R and F978R) were not rescued by cyclosporine A (Fig. 7). Login to comment
213 Mutants L65R(TM1), A129R(TM2), F732R(TM7), Y950R(TM11), Y953R(TM11), and F978R- (TM12) showed partial activity (about 25-50% of wild-type activity), whereas the maximal tariquidar-stimulated ATPase activity of mutants H61R(TM1), G64R(TM1), F303R(TM5), F343R(TM6), Q725R(TM7), V865R(TM10, Q946R(TM11), and L975R(TM12) was about 50-100% of wild-type enzyme. Login to comment