ONLINE SUPPLEMENTAL MATERIAL

In addition to this text document, Supplemental information contains one table and three figures. In a series of workbook sheets, Table S1 reports unfiltered mass spectrometry data reported, including computational scoring. These data relate to Figure 1B, Figure 3A and Figure 3B. Figure S1. Relates to Figure 2F. SLK luciferase assay (Figure S1 panel A) activates NRF2 signaling in an ETGE-independent manner. NRF2 luciferase assay (Figure S1 panel B) was included as a positive control for ETGE-dependent regulation of NRF2-mediated transcription. Figure S2. Relates to Figure 7A-D, and G. Included in supplemental data to show that there is differential expression of DPP3 across SQCC. Figure S3. Relates to Figure 7E and F. Luciferase data in Figure S3 panel A was completed in KEAP1 knockout mouse embryonic fibroblasts to demonstrate that wild type KEAP1 expression in HEK293T cells does not affect the results. The Western blot depicted in Figure S3 panel B demonstrates that each KEAP1 mutation tested is expressed and binds both NRF2 and DPP3.

Supplemental Methods

siRNA sequences: DPP3#1 (CAC CAA AUC CAA UGC UCC UCA CAU A), DPP3#2 (GCU UAC CAU CCU GUC UAC CAG AUG A), DPP3#3 (CCC UCC AUU CGU GUG UGU AUU UAG G), NRF2 (GUA AGA AGC CAG AUG UUA A), KEAP1 (GGG CGU GGC UGU CCU CAA U). Control siRNAs were obtained from Life Technologies; sequences are as follows: CGU ACG CGG AAU ACU UCG ATT and UCG AAG UAU UCC GCG UAC GTT.

Cell lysis buffers: 0.1% NP40 (10% glycerol, 50mM HEPES, 150 mM NaCl, 2mM EDTA, 0.1% NP-40) containing protease inhibitor mixture (Thermo Scientific) and phosphatase inhibitor (Thermo Scientific). RIPA buffer (1% NP-40, 0.1% SDS, 0.25% sodium deoxycholate, 150mM NaCl, 10% glycerol, 25mM Tris, 2mM EDTA). Additionally, NRF2 ubiquitination experiments were performed in the presence of 2mM N-ethylmaleimide.

Cell Staining Buffers: cytoskeletal buffer (5 mM PIPES, pH 6, 137 mM NaCl, 5 mM KCl, 1.1 mM Na2HPO4, 0.4 mM KH2PO4, 0.4 mM MgCl2, 0.4 mM NaHCO3, 2 mM EGTA, 50mM glucose).

Antibodies employed for W. blot analysis: anti-FLAG M2 monoclonal (Sigma), anti-HA monoclonal (Roche), anti-FAM117b (ProteinTech, 21768), anti-MAD2L1 (Bethyl, Montgomery TX, A300-301A), anti-MCM3 (Bethyl, A300-192A), anti-SLK (Bethyl, A300-499A), anti-bactin polyclonal (Sigma, A2066), anti-btubulin monoclonal (Sigma, T7816), anti-KEAP1 polyclonal (ProteinTech, Chicago IL), anti-DPP3 polyclonal (abcam, Cambridge MA, 97437), anti-GFP (abcam, ab290), anti-NRF2 H300 polyclonal (Santa Cruz, Santa Cruz CA), and anti-VSV polyclonal (Bethyl, A190-131A). Quantitative PCR primers: GCLM (F: ACAGCGAGGAGCTTCATGATTG, R: CTCCCTGACCAAATCTGGGTTG), HMOX1 (F: GGCCAGCAACAAAGTGCAAGATTC, R: AGCAACTGTCGCCACCAGAAAG), GAPDH (F: ATGGGGAAGGTGAAGGT, R: AAGCTTCCCGTTCTCAG).

Protein Identification, Filtering and Bioinformatics: All raw data were converted to mzXML format before a search of the resultant spectra using SorcererTM-SEQUEST® (build 4.0.4, Sage N Research) and the Transproteomic Pipeline (TPP v4.3.1). Data were searched against either the human UniProtKB/Swiss-Prot sequence database (Release 2011_08) or the human IPI database (Version 3.87), both supplemented with common contaminants, i.e. porcine (Swiss-Prot P00761) and bovine (P00760) trypsin, and further concatenated with its reversed copy as a decoy (40,494 total sequences). Search parameters used were a precursor mass between 400 and 4500 amu, up to 2 missed cleavages, precursor-ion tolerance of 3 amu, accurate mass binning within PeptideProphet, semi-tryptic digestion, a static carbamidomethyl cysteine modification, and variable methionine oxidation. False discovery rates (FDR) were determined by ProteinProphet and minimum probability cutoffs resulting in a 1% FDR were selected individually for each experiment. PeptideProphet/ProteinProphet results for each AP-MS experiment were stored in a local Prohits database. Prohits performed the mapping of UniProtKB/IPI accession identifiers to IDs. These results were then imported into Cytoscape v2.8.2 for network visualization and SPOTLITE for interaction prediction. annotations were imported from NCBI Entrez Gene through Cytoscape. Known protein-protein interactions were extracted from the BioGRID database (Release 3.1.89).