Tubulin polyglutamylation plays an important role for several MT-related processes, such as motility of cilia and flagella, stability of centrosomes, and neurite outgrowth. Glutamylation is catalyzed by polyglutamylases, also called as tubulin tyrosine ligase-like (TTLL) enzymes[].TTLL-4 is a polyglutamylase which preferentially modifies beta-tubulin and nucleosome assembly proteins NAP1 and NAP2. It is involved in the side-chain initiation step of the polyglutamylation reaction rather than in the elongation step [, ]. In Caenorhabditis elegans, it is involved in side-chain polyglutamylation of tubulin in sensory cilia [].