Posttranslational modifications of α- and β-tubulin in Giardia lamblia, an ancient eukaryote

Tubulin of Giardia lamblia, a representative of the oldest eukaryotes, was screened for posttranslational modifications, Mass spectrometry of the carboxy-terminal peptides documents a large number of variants, Both alpha-and beta-tubulin show polyglycylation with up to 20 and 15 extra glycyl residues respectively. Minor variants show a low level of glutamylation without or with glycylation. The glutamylation-specific antibody GT335 detects alpha- and beta-tubulin in immunoblots, The terminal tyrosine is fully retained in alpha-tubulin, which is completely acetylated at Lys-40, Thus except for the detyrosinationl/tyrosination cycle all posttranslational modifications known for higher eukaryotes are already present in Giardia. (C) 1997 Federation of European Biochemical Societies.