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. 2021 Jan 7;12(1):42. doi: 10.1038/s41419-020-03299-8

Fig. 2. PSMB5 is a target of TRIB2 in the proteasome.

Fig. 2

a Schematic representation of the assembly and composition of the proteasome. b TRIB2 affected Ub levels independent of proteasome assembly. Ub levels were measured in the control, Bel-7402, and SMMC-7721 cells with or without TRIB2 knocked down and with or without POMP knocked down. c, d PSMB5 of 20S CP, but not 19S RP, was involved in the TRIB2-mediated effects on Ub level. Ub levels in the Bel-7402 and SMMC-7721 cells with or without TRIB2 knocked down and treated with DMSO, b-AP15 (5 µM, 24 h) (c), ZACD (100 µM, 24 h), TLCK (50 μM, 24 h), or BTZ (100 nM, 24 h) (d), as indicated. e PSMB5 was critical for TRIB2. Ub was measured in the Bel-7402 and SMMC-7721 cells with or without PSMB5 knocked out or compensatory PSMB5 expression, in the presence or absence of TRIB2 knockdown. f, g Ub at WCL and in proteasomes isolated from the Bel-7402 cells with TRIB2 knocked down or overexpressed, in the presence or absence of PSMB5. The samples derived from the same experiment using control beads had been processed in parallel. The levels of conj & poly Ub were normalized to that of GAPDH at WCL (f), while normalized to that of PSMB3 in the isolated proteasome (g). Images of all the immunoblots are representative of three independent experiments. The relative protein levels of the conj & poly Ub and mono Ub were normalized to those of GAPDH as calculated by ImageJ software and indicated just below the blots (b–f).