Expression of HA7Q-htt and 3xFlag7Q-htt in selected brain regions. (A) Confocal microscopy of HA epitope (HA), 3xFlag7Q epitope (FLAG), and htt (Htt) expression in the 24 month-old Hdh 3xFlag7Q/HA7Q striatum and cortex. Nuclei were visualized with the DNA dye To-Pro-3 (blue). Arrows indicate examples of where co-localization of the HA and 3xFlag epitopes, or of the epitopes with htt occurs. Scale bar = 25 μm. (B) Western blot analysis of HA7Q-htt (left panel) and 3xFlag7Q-htt (right panel) in 50 μg total protein isolated from Hdh HA7Q/+ and Hdh 3xFlag7Q/+ testis and various brain regions (brain stem: br stem, cerebellum: cb, thalamus: thal, striatum: str, and cortex: ctx). The antibodies used (monoclonal antibodies HA.11 and MAb FLAG M2) and the position of a 200 kD protein marker are indicated.