FIGURE 1.
SiRNA-mediated suppression of TRAPβ/SSR2 or TRAPδ/SSR4 in INS832/13 cells. A, Structure and subunit composition of the TRAP/SSR complex as predicted by bioinformatic analysis. B, Immunoblotting with the listed antibodies of INS832/13 cell lysates transfected with the indicated siRNAs. Proinsulin was measured with rodent-specific anti-proinsulin. Tubulin is a loading control. C, Quantitation (mean ± SD) of TRAP/SSR subunit protein levels from experiments like that in panel B (n = 4). *P < .05, **P < .01 comparing to WT. D, Quantitation (mean ± SD) of proinsulin and insulin protein levels from experiments like that in panel B (n = 4). *P < .05, **P < .01 compared to WT. E, Scrambled oligo (NC) or TRAPβ/SSR2 or TRAPδ/SSR4 siRNA-mediated gene suppression cells were pulse-labeled with 35S-Met/Cys for 10 minutes (left panel). Cell lysates (normalized to TCA-precipitable counts) were subjected to immunoprecipitation with anti-insulin, followed by SDS-PAGE and phosphorimaging. Quantitation of proinsulin (n = 3) is shown at right. *P < .05, **P < .01