RNF26 promotes polyubiquitination of MITA at K150.

(A) RNF26 mediated polyubiquitination of MITA at K150. The 293 cells (5×10⁶) were transfected with HA-Ub (1 µg) and RNF26 (1 µg) together with Flag-MITA or the indicated mutants (5 µg each). Twenty-four hours after transfection, cells were subjected IP under denatured conditions with anti-Flag and immunoprecipitates were analyzed by immunoblots with anti-HA (upper panel) or anti-Flag (lower panel). The whole cell lysates were analyzed by immunoblots with anti-Flag or anti-RNF26 as indicated. (B) RNF26 targeted MITA for polyubiquitination at K150 in vitro. RNF26, MITA and its mutants were obtained by in vitro transcription and translation. Biotin-Ub, E1, UbcH5 and RNF26 were incubated with MITA or its mutants. The ubiquitination of MITA was examined by immunoblot analysis with HRP-streptavidin (top panel). The inputs of RNF26 and MITA were analyzed by immunoblots with anti-MITA and anti-RNF26 (bottom panels). All experiments were repeated for at least three times with similar results.