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. Author manuscript; available in PMC: 2015 Feb 1.
Published in final edited form as: Nat Protoc. 2014 Jul 10;9(8):1867–1881. doi: 10.1038/nprot.2014.127

Figure 5. Minimum Difference Comparison (MinDC) highlights triple mutant interactions that differ markedly from the corresponding double mutant interactions.

Figure 5

The left heatmap displays S-scores from a TMA screen of query mutants AΔ and BΔ against a library of deletion mutants (1Δ-4Δ). AΔ BΔ display negative interactions with 1Δ-3Δ, which could be indicative of A and B being redundant with respect to the functions represented by proteins 1-3. However, the triple mutant interaction is not meaningful if either of the single mutants (AΔ or BΔ) displays the same interaction with the corresponding library mutant. The MinDC score was devised to emphasize the cases in which only the triple mutant displays a strong defect. To this end, the S-score of the more severely affected double mutant is subtracted from the S-score of the triple mutant, and the difference constitutes the MinDC score. Thus, the MinDC score for 1Δ is strongly negative, whereas that for 3Δ is neutral since the S-score of AΔ BΔ 3Δ equals that of AΔ 3Δ. As seen for 4Δ, a positive MinDC score can identify cases where the triple mutant alleviates the defect observed in the sickest double mutant.