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. 2022 Nov 19;25(12):105626. doi: 10.1016/j.isci.2022.105626

Figure 2.

Figure 2

BRCA1 protein interacts with and ubiquitinates PERK and IRE1

(A–D) Total protein extracts were isolated from (A) control or BRCA1-depleted MCF7, (B) control or BRCA1-depleted MDA-MB-231cells, (C) MDA-MB-436 cells (+ or def), and (D) control, BRCA1 or BARD1 over-expressing MDA-MB-436 BRCA1-def cells.

(E and F) Immunoprecipitation (IP) of BRCA1 protein pull-downs of PERK and IRE1 from MCF7 (E) or MDA-MB-231 (F) cytoplasmic protein extract. BRCA1 IB: ∗ = hyperphosphorylated BRCA1, ∗∗ = truncated BRCA1. ∗∗∗ = delta11q isoform. IRE1 IB: ∗ = possible ubiquitinated IRE1.

(G and H) Ubiquitination analysis of PERK and IRE1 in (G) MCF7 cells or (H) MDA-MB-231 cells. Cells were transfected with control or BRCA1 siRNA. BRCA1 siRNA transfected cells were either untreated or treated with DMSO or Bortezomib overnight before harvesting for protein analysis.

(I and J) In vitro ubiquitination analysis of (I) PERK or (J) IRE1 with E1, UBE2J1, BRCA1, BARD1, and/or ubiquitin. Ubiquitinated PERK or IRE1 was detected with an anti-Ub antibody. Ub = Ubiquitin. Bortz = Bortezomib. Data are represented as mean ± SD. P value was calculated by Student’s two-tailed, unpaired t-test. ∗ <0.05. See also Figures S4–S6.