Extended Data Fig. 5. SND1 binds to Tap1/2 and promotes their degradation.

a, Endogenous SND1 knockdown in Py8119-OVA cells was confirmed with western blot. b, Tap1/2 mRNA levels in the indicated Py8119-OVA cells that were co-cultured with OT-I splenocytes for 0 or 24 hr was examined by qRT-PCR. n=3 independent experiments. c, Indicated Py8119-OVA tumor cells co-cultured for 24 hr were treated with 10 μg/ml of actinomycin D for another 8 hr. RNA levels of Tap1/2 in tumor cells were determined by qRT-PCR. n=3 independent experiments. d-g Py8119-OVA cells with SND1 (d) or MTDH (f) knockdown were subjected to RIP assay after 24 hr co-culture. The interaction between SND1 or MTDH and Tap1/2 was determined by PCR. Tap1/2 RNAs that bind to MTDH (e) or SND1 (g) were quantified and normalized to the pulled down MTDH and SND1 levels, respectively. n=3 independent experiments. h, Electrophoretic mobility gel shift assay was performed with in vitro transcribed TAP1/2 mRNA incubated with PBS, recombinant MTDH and SND1 alone or in combination. Data represent mean ± SEM. Significance determined by one-way ANOVA analysis with Dunnett’s test for multiple comparisons (b,c,e), or two tailed Student’s t-test (g). Numerical source data for b, c, e, g,and uncropped images for a, d, f, h are provided.