Evaluating the identity of ubiquitinated and ubiquitin-associated proteins tandem co-purifying non-covalently with wild-type (17 glutamine) human Huntingtin fragment, amino acids 1-502 C-terminally tagged with the HA peptide epitope, basally expressed from the CMV promoter within vector pcDNA3.1 transiently transfected into striatal precursor cell line St14A, significantly elevated above cells transfected with empty pcDNA3.1 vector negative control, in cells co-transfected with human FLAG-ubiquitin.