C) Representative immunoblots of brain extracts of wild-type, Ttll1-/- and Ttll7-/- mice. Polyglutamylation of α-tubulin, detected with polyE and GT335, is specifically lost in Ttll1-/- brain. By contrast, β-tubulin glutamylation, which is specifically detected with β‑monoE, is absent from brains of Ttll7-/- mice. D) Representative immunoblots of extracts of wild-type, Ttll1‑/- and Ttll7-/- primary hippocampal neurons at DIV4. As in brain (C), α-tubulin polyglutamylation is specifically lost in Ttll1-/- neurons, while β-tubulin glutamylation lacks in Ttll7-/- neurons. E 