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. Author manuscript; available in PMC: 2016 Oct 1.
Published in final edited form as: Neurobiol Dis. 2015 Jun 30;82:281–288. doi: 10.1016/j.nbd.2015.06.017

Fig. 5.

Fig. 5

UBQLN2 selectively interacts with mutant HTT through the UBA domain. (A) Diagram of UBQLN2, HTT and ATXN3 expression constructs. (B-C) In HEK293 cells, flag-tagged UBQLN2, ΔUBA or ΔUBL was co-expressed with GFP-HTT25Q or GFPHTT103Q (B) or with GFP-ATXN3-28Q or GFP-ATXN3-84Q (C). HTT or ATXN3 in lysates from transfected cells was immunoprecipitated (IP) with anti-GFP antibody (B) or anti-1H9 antibody (C). Co-precipitated UBQLN2 was detected by IB with anti-FLAG antibody (B-C), shown on top panels. Input levels of the expressed proteins are shown on the bottom. UBQLN2 selectively interacts with an N-terminal HTT fragment with a 103Q expansion but not with normal or expanded ATXN3; deletion of the UBA domain of UBQLN2 attenuates interaction with HTT-103Q. Lysates and IP samples were also probed with anti-ubiquitin antibody, which did not reveal specific ubiquitinated forms of HTT or ATXN3. In B-C, vector represents co-transfected empty vector plasmid.