ABCMdb

ABCB1 p.Tyr790Ala

Predicted by SNAP2:	A: N (82%), C: N (93%), D: N (66%), E: N (72%), F: N (93%), G: N (82%), H: N (93%), I: N (87%), K: N (72%), L: N (93%), M: N (87%), N: N (78%), P: N (61%), Q: N (82%), R: N (82%), S: N (93%), T: N (87%), V: N (87%), W: N (72%),
Predicted by PROVEAN:	A: N, C: N, D: N, E: N, F: N, G: D, H: N, I: N, K: N, L: N, M: N, N: N, P: D, Q: N, R: N, S: N, T: N, V: N, W: N,

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Publications
[hide] The Transmission Interfaces Contribute Asymmetrica... J Biol Chem. 2015 Jul 3;290(27):16954-63. doi: 10.1074/jbc.M115.652602. Epub 2015 May 18. Loo TW, Clarke DM
The Transmission Interfaces Contribute Asymmetrically to the Assembly and Activity of Human P-glycoprotein.
J Biol Chem. 2015 Jul 3;290(27):16954-63. doi: 10.1074/jbc.M115.652602. Epub 2015 May 18., [PMID:25987565]

Abstract [show]
P-glycoprotein (P-gp; ABCB1) is an ABC drug pump that protects us from toxic compounds. It is clinically important because it confers multidrug resistance. The homologous halves of P-gp each contain a transmembrane (TM) domain (TMD) with 6 TM segments followed by a nucleotide-binding domain (NBD). The drug- and ATP-binding sites reside at the interface between the TMDs and NBDs, respectively. Each NBD is connected to the TMDs by a transmission interface involving a pair of intracellular loops (ICLs) that form ball-and-socket joints. P-gp is different from CFTR (ABCC7) in that deleting NBD2 causes misprocessing of only P-gp. Therefore, NBD2 might be critical for stabilizing ICLs 2 and 3 that form a tetrahelix bundle at the NBD2 interface. Here we report that the NBD1 and NBD2 transmission interfaces in P-gp are asymmetric. Point mutations to 25 of 60 ICL2/ICL3 residues at the NBD2 transmission interface severely reduced P-gp assembly while changes to the equivalent residues in ICL1/ICL4 at the NBD1 interface had little effect. The hydrophobic nature at the transmission interfaces was also different. Mutation of Phe-1086 or Tyr-1087 to arginine at the NBD2 socket blocked activity or assembly while the equivalent mutations at the NBD1 socket had only modest effects. The results suggest that the NBD transmission interfaces are asymmetric. In contrast to the ICL2/3-NBD2 interface, the ICL1/4-NBD1 transmission interface is more hydrophilic and insensitive to mutations. Therefore the ICL2/3-NBD2 transmission interface forms a precise hydrophobic connection that acts as a linchpin for assembly and trafficking of P-gp.

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Sentences [show]
No. Sentence Comment
131 Mutants V907S (IH4) and Y790A (ICL3) represent examples of mutations that partially inhibited maturation. Login to comment
133 Mutation of Tyr-790 to alanine substantially reduced maturation as about 85% of the product was the 150 kDa immature protein. Login to comment
137 For example, the total P-gp yields in mutants R789A, V907S, Y790A, and V908S (Fig. 2A) were about 60, 75, 75, and 98% of wild-type P-gp, respectively. Login to comment
147 A, representative immunoblot of SDS extracts of whole cells transfected with wild-type P-gp (WT), control vector (Cont), or P-gp mutants R789A, V907S, Y790A, or V908S showing no maturation (R789A), partial maturation (V907S, Y790A) or maturation similar to wild-type P-gp (V908S). Login to comment