Figure 5

ERβ degrades ARNT via the ubiquitin-proteasome system. (a) HEK293 cells were transfected with hERβ. At 36 h post-transfection, cells were treated with 10 μM MG132 for 12 h. The total protein extracts were immunoblotted with ARNT antibody and reprobed with actin antibody. Values represent the mean ± S.D. (N = 3). * P <0.01. All experiments were repeated at least three times. (b) HEK293 cells in 100Q dish were transfected with His-Ubi (10 μg) and ARNT plasmid (10 μg) or hERβ (10 μg) as indicated. At 36 h post-transfection, cells were treated with 10 μM MG132 for 12 h. Immunoprecipitated ARNT or His-Ubi-conjugated ARNT was detected using anti-ARNT or anti-ubiquitin antibody, respectively. Arrows indicate the ubiquitinated ARNT protein bands. Molecular weight markers are as shown. The molecular mass of the human ARNT is 95 kDa. Shown are representative results from two separate experiments.