Figure 5.

Viperin stimulates ubiquitination of IRAK1. HEK 293T cells were transfected with genes encoding IRAK1, TRAF6, viperin, or viperinΔ3C as indicated. 30 h post-transfection cell lysates were prepared and analyzed by immunoprecipitation (IP) (IRAK1 as bait protein) followed by immunoblotting (IB) with anti-ubiquitin antibody. GAPDH was used as a loading control. A representative blot is shown. A significant increase in ubiquitinated proteins is only observed in cells expressing viperin and IRAK1; viperinΔ3C fails to stimulate ubiquitination. Ubiquitination was quantified for each condition using ImageJ software and compared and presented as mean ± S.E. (n = 3) with *** indicating p < 0.001 (Student's t test for independent samples).