Auto-Regulated Ubiquitylation of Other USP-Family DUBs
(A) HA-ubiquitin (HA-Ub) immunoprecipitations (in presence of βME) retrieved USP4 CD, USP15 CD, and USP11 CD (wild-type USP4, USP15, and USP11 were not or weakly detected under these conditions).
(B) HA-Ub immunoprecipitations from U2OS cell extracts that were processed without βME retrieved modified forms of USP4 CD, USP15 CD, and USP11 CD (exp., exposure).
(C) HA-Ub immunoprecipitations from U2OS cell extracts retrieved USP15 CD-C451A less efficiently than USP15 CD.
(D) USP15 WT, WT-C451A, and CD-C451A but not CD immunoprecipitations from U2OS cell extracts (see Figure S7B for inputs) efficiently retrieved SMAD2/3. See also Figure S7.