POLYGLYCYLATION OF TUBULIN - A POSTTRANSLATIONAL MODIFICATION IN AXONEMAL MICROTUBULES

A posttranslational modification was detected in the carboxyl-terminal region of axonemal tubulin from Paramecium. Tubulin carboxyl-terminal peptides were isolated and analyzed by Edman degradation sequencing, mass spectrometry, and amino acid analysis. All of the peptides, deriv ed from both alpha and beta tubulin subunits, were modified by polygly cylation, containing up to 34 glycyl units covalently bound to the gam ma carboxyl group of glutamyl residues. This modification, present in one of the most stable microtubular systems, may influence microtubule stability or axoneme function, or both.