Fig. 4.

TDP-43 and TDP-S6 display post-translational modifications reminiscent of biochemical signature observed in neurodegeneration. The cells were transfected with mock, HA-TDP-43, or HA-TDP-S6 plasmids and extracted by a Sarkosyl buffer (A), and the pellet was solubilized with urea buffer (B). The sequentially solubilized proteins were analyzed by Western blotting (WB). In detergent-insoluble fractions, modified TDP-43 phosphorylated species (marked by asterisks), proteolytic fragments (marked by arrowheads), and high molecular mass TDP immunoreactivity are observed. An increase in global protein ubiquitination with TDP-43 and more dramatically with TDP-S6 overexpression is observed using a Ub-specific antibody (B, right panel).