Fig. 6

ARMC5 controls the degradation of most Pol II subunits under physiological conditions. A, B ARMC5 KO resulted in the accumulation of the 12 Pol II subunits. The protein levels of all 12 Pol II subunits (POLR2A-2L) in WT and KO MEF cells were determined by immunoblotting. Representative immunoblotting is shown in A. Pol II subunits, β-actin and α-actinin signals were quantified by densitometry, and signal ratios of the subunits versus β-actin or α-actinin of paired WT and KO samples (linked by lines) are presented in B. C mRNA levels of most Pol II subunits remained unchanged in KO MEFs. The mRNA levels of the subunits in the WT and KO MEFs were measured by RT-PCR, and the results are shown as the signal ratios of subunits versus Rn7sk. The number (n) of independent experiments is indicated. *p < 0.05; **p < 0.01; ***p < 0.001 (two-way Student’s t tests). D A 3D model of the Pol II and ARMC5-CUL3-RBX1 E3 complex. This dimeric E3 is shown to interact with two Pol IIs via POLR2A. The protein structures of all the components were obtained from PDB and AlphaFold2. The components are positioned in this 3D model according to the existing structural information from PDB and our previous binding and deletion studies [45]. Only the visible Pol II subunits in this viewing angle are marked