Fig 1: Cellular TRIM33 is only TIF1 family member that negatively regulates HIV-1 integrase stability. a Schematic representation of domain organization of TIF1 subfamily members. b Effect of anti-TRIM24 siRNAs. The immunoblots show the levels of TRIM24, TRIM33, TRIM28, and HIV-1 IN in HeLa cells transfected with individual siRNAs against TRIM24 (#4, #5, #6, and #7), their pool (Pool) or non-targeting siRNA-2 (siNT2). MG132 was used to assess the effect of inhibiting proteasome-mediated protein degradation. c Effect of anti-TRIM28 siRNAs. Same as in panel b using siRNAs against TRIM28. d Effect of anti-TRIM33 siRNAs. Same as in panel b using siRNAs against TRIM33. e Stability of HIV-1 IN protein in siRNA-treated cells. Representative immunoblots showing the levels of HIV-1 IN after HeLa cell transfection with siRNAs against TRIM33, Pin1, and LEGF/p75 at different times and treatment with cycloheximide (30 µg/ml) to block protein degradation. Tubulin served as a loading control. f Quantification of HIV-1 IN levels. Experiments were performed as in panel e. IN amounts are normalized to Tubulin and expressed as percent over IN at time = 0 for each treatment. Data are mean ± SEM; n = 3 independent experiments. g Effects of siRNAs on the levels of HIV-1 and MLV IN proteins. The figure shows representative immunoblots using lysates of HeLa cells transfected to express either Flag-IN from HIV-1 (upper part) or MLV-IN (lower part)and siRNAs against the indicated factors. Tubulin and HSC70 served as loading controls. h Quantification of the effects of siRNAs against the indicated factors or treatment with MG132 on the levels of HIV-1 IN. IN levels are expressed after normalization for tubulin and as fold over non-targeting siRNA siNT1. Data are mean ± SEM; n = 3 independent experiments; *P < 0.05; **P < 0.01; one-way ANOVA. i Same as in panel g for MLV-IN. Normalization was for cellular HSC70. Data are mean ± SEM; n = 3 independent experiments; *P < 0.05; one-way ANOVA