Probable polyglutamylase that forms polyglutamate side chains on tubulin (PubMed:27635036). Probably acts when complexed with other proteins (PubMed:27635036). Appears to be dispensable for polar spindle formation in dividing embryonic cells, for cilia-dependent osmotic avoidance and for male mating behavior (PubMed:27635036). Regulates microtubule dynamics in uterine muscle cells (PubMed:24780738). Expressed in hypodermis and pharyngeal muscles. Expressed in embryos and adults. RNAi-mediated knockdown at the L1 larval stage causes a reduction in egg-laying, likely due to a defect in the egg-laying apparatus muscles. Belongs to the tubulin--tyrosine ligase family.