Enhances the tyrosine carboxypeptidase activity of VASH1 and VASH2, thereby promoting the removal of the C-terminal tyrosine residue of alpha-tubulin (PubMed:29146868). Also required to enhance the solubility and secretion of VASH1 and VASH2 (By similarity). Plays a role in axon and excitatory synapse formation (PubMed:31235911). Interacts with VASH1 and VASH2. Detected both intracellularly and extracellularly (PubMed:20736312). Within cells, localizes mainly to the apical part of the cell (PubMed:20736312). Highly expressed in bone marrow, spleen and testis. Belongs to the SVBP family.