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. 2013 Jan 9;110(5):E358–E367. doi: 10.1073/pnas.1216948110

Fig. 6.

Fig. 6.

Control of Drs2 PS recognition by both cytosolic and exofacial residues. (A) DRS2 alleles harboring cytosolic cluster (exit gate) mutations complement the cold sensitivity of a drs2Δ strain. (B) Influence of exit gate mutations on PS asymmetry measured by sensitivity to PapB. Relative to WT Drs2, Drs2[F511Y] displays a defect in PS asymmetry. Drs2 N445S maintains WT resistance to PapB, whereas Drs2 N445S, [F511Y] slightly exacerbates the Drs2[F511Y] defect. (C) DRS2 alleles harboring combination entry and exit gate mutations complement the cold sensitivity of a drs2Δ strain. (D) Relative to WT Drs2, Drs2[QQ→GA] displays a major loss of PS asymmetry, which can be restored by mutation of a cytosolic cluster residue (Drs2[QQ→GA], N445S) to permit increased PS recognition. (E) Influence of cytosolic cluster mutations on PE asymmetry measured by sensitivity to duramycin. Relative to WT Drs2 and drs2∆, each mutant maintains normal PE asymmetry. Therefore, Drs2[QQ→GA] exhibits a specific defect in PS transport. (F) Combining the QQ→GA substitution with either D473K or F511Y does not disrupt PS asymmetry further or restore PS asymmetry. However, the exit gate mutation N445S can restore PS asymmetry to Drs2[QQ→GA] and Drs2[QQ→GA], [D473K]. Compare Drs2[QQ→GA], N445S with Drs2[QQ→GA] and Drs2[QQ→GA], [D473K], N445S with Drs2[QQ→GA], [D473K]. For all experiments, values are the mean (±SEM).