Enhances the tyrosine carboxypeptidase activity of VASH1 and VASH2, thereby promoting the removal of the C-terminal tyrosine residue of alpha-tubulin (PubMed:29146869, PubMed:31270470, PubMed:31235911, PubMed:31324789, PubMed:31171830, PubMed:31235910). This activity is critical for spindle function and accurate chromosome segregation during mitosis since microtuble detyronisation regulates mitotic spindle length and postioning (PubMed:31171830). Also required to enhance the solubility and secretion of VASH1 and VASH2 (PubMed:20736312, PubMed:27879017, PubMed:30607023). Plays a role in axon and excitatory synapse formation (PubMed:31235911). Interacts with VASH1 and VASH2. Detected both intracellularly and extracellularly (By similarity). Within cells, localizes mainly to the apical part of the cell (By similarity). The disease is caused by variants affecting the gene represented in this entry. Belongs to the SVBP family.