Metallocarboxypeptidase that mediates protein deglutamylation of tubulin and non-tubulin target proteins (PubMed:21074048, PubMed:25103237, PubMed:26829768, PubMed:29593216). Catalyzes the removal of polyglutamate side chains present on the gamma-carboxyl group of glutamate residues within the C-terminal tail of tubulin protein (PubMed:21074048, PubMed:25103237). Specifically cleaves tubulin long-side-chains, while it is not able to remove the branching point glutamate (PubMed:25103237). Also catalyzes the removal of polyglutamate residues from the carboxy-terminus of non-tubulin proteins such as MYLK (PubMed:21074048). Mediates the deglutamylation of nucleotidyltransferase CGAS, leading to CGAS antiviral defense response activation (PubMed:26829768). Involved in KLF4 deglutamylation which promotes KLF4 proteasome-mediated degradation, thereby negatively regulating cell pluripotency maintenance and embryogenesis (PubMed:29593216). (L-glutamyl)(n+1)-gamma-L-glutamyl-L-glutamyl-[protein] + H2O = (L-glutamyl)(n)-gamma-L-glutamyl-L-glutamyl-[protein] + L-glutamate C-terminal L-alpha-aminoacyl-L-glutamyl-L-glutamyl-[tubulin] + H2O = C-terminal L-alpha-aminoacyl-L-glutamyl-[tubulin] + L-glutamate Binds 1 zinc ion per subunit. Interacts with MYLK. Colocalizes with gamma-tubulin in the centrioles at interphase and dividing cells and with glutamylated tubulin in basal bodies of ciliated cells. Widely expressed. Expressed abundantly in testis, pituitary and brain and to a lower extent in eye, stomach, adrenal and kidney. In brain, expressed at low level in cerebellum as compared to cortex. Mice are more vulnerable to DNA virus infection due to impaired immune response. Knockout mice promote somatic cell reprogramming and higher litter size at birth (PubMed:29593216). Knockout blastocytes show enhanced development (PubMed:29593216). Belongs to the peptidase M14 family.