Nguyen Supplemental Experimental Procedures

For immunoprecipitations of endogenous acetylated α tubulin, expression constructs were overexpressed in HEK293 cells (3X106) using FuGENE 6 (Roche Applied Science, Schaarbeeklei, Belgium), as indicated in the figures. 24 hours after transfection, cells were washed with PBS and lysed in a buffer containing 50mM Tris-HCl pH7.5, 1mM EDTA, 1% NP-40, 500mM NaCl and protease inhibitors (Zhang et al., 2007). Ectopically expressed Flag-or Myc-tagged proteins were immunoprecipitated by using a polyclonal anti-Flag or anti-Myc antibodies overnight at 4°C followed by 1 hour incubation with protein A-agarose beads (Santa Cruz, Bioconnect, The Netherlands). Anti-HA immunoprecipitation was carried out as negative control. Immunoprecipitates were washed twice with lysis buffer and four times with another lysis buffer (25mM Hepes, 150mM NaCl, 1.5 % Triton, 10 % glycerol, 1mM Na3VO4, 25mM β-glycerophosphate, 1mM NaF) and subjected to SDS-PAGE for subsequent Western blot analysis. Monoclonal anti-ELP1 and polyclonal anti-Elp3,-Elp4 and-Elp5 antibodies for Western blot analyses were purchased from BD Biosciences Pharmingen and previously described (Petrakis et al., 2004), respectively. Antisera against two ELP3 peptides (GPDSDFEYSTQSYTGY and ARYDPFLQTRHRIEQL) were produced by Eurogentec (Liège, Belgium) and used in immunoprecipitation studies. Monoclonal anti-acetylated α tubulin (1:30000),-Tyr α tubulin (1:30000),-α tubulin (1:30000) (used for Western blot analyses) and polyclonal anti-Flag antibodies (used for immunoprecipitation experiments) were from Sigma. Polyclonal anti-HDAC6 (1:2000) antibody used for Western blots was from Santa Cruz as well as the polyclonal anti-HA and anti-Myc antibodies used for immunoprecipitations. For immunoprecipitation of endogenous proteins, cells were washed with PBS and lysed in