Metallocarboxypeptidase that mediates protein deglutamylation of tubulin and non-tubulin target proteins (PubMed:21074048, PubMed:22170066, PubMed:25103237, PubMed:30420557, PubMed:29593216). Catalyzes the removal of polyglutamate side chains present on the gamma-carboxyl group of glutamate residues within the C-terminal tail of alpha- and beta-tubulin (PubMed:22170066, PubMed:25103237, PubMed:30420557). Specifically cleaves tubulin long-side-chains, while it is not able to remove the branching point glutamate (PubMed:21074048). Also catalyzes the removal of polyglutamate residues from the carboxy-terminus of alpha-tubulin as well as non-tubulin proteins such as MYLK (PubMed:21074048, PubMed:22170066). 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. Localizes in both the cytoplasm and nuclei of interphase and dividing cells. Widely expressed. Highly expressed in the cerebellum and cortex of adult mouse brain. Expressed at similar levels in both the cerebellum and the cortex throughout all developmental stages. Also expressed in sciatic nerve transection, spinal motor neurons undergoing axon regeneration, testis, heart, eye, lung, pancreas, intestine, stomach, pituitary, spleen, adrenal, kidney and in developing brain. Expression in cranial motor nuclei is the same as that observed in uninjured primary motor neurons. Expression is prevalent in sensory neurons and hippocampal CA3 neurons in addition to regenerating motor neurons. Highly expressed in differentiating neurons. From 16.5 dpc, expression is widespread in brain, spinal cord, and peripheral nervous tissue. Within the developing CNS, expression is restricted to regions of brain and spinal cord containing differentiating neurons. By axonal regeneration. Defects in Agtpbp1 are the cause of Purkinje cell degeneration (pcd). Pcd is a spontaneous mutation that results in adult-onset degeneration of cerebellar Purkinje neurons, retinal photoreceptors, olfactory bulb mitral neurons and selected thalamic neurons, and causes defective spermatogenesis. Pcd mice also manifest cerebellar atrophy and a peripheral nerve degeneration resulting in pure motor or motor-predominant neuropathy. Motoric femoral quadriceps nerves are characterized by reduced total calibers, a loss of myelinated axons, perturbed axon morphology, and macrophage activation. The amount of motor neurons in the ventral horns of lumbar spinal cords is reduced. These anomalies are accompanied by dysregulated tubulin polyglutamylation (PubMed:30420557). Defects in mitochondrial metabolic functions are also observed. The molecular causes of neurodegeneration are probably due to an accumulation of glutamylation, either tubulin hyperglutamylation or another hyperglutamylated target proteins. An increase of intranuclear localization of lysyl oxidase (Lox) propeptide, which interferes with NF-kappa-B Rela signaling and microtubule-associated protein regulation of microtubule stability is also observed, possibly leading to underdevelopment of Purkinje cell dendrites. Knockout pcd mice show hyperglutamylation of alpha- and beta-tubulins in the brain (PubMed:22170066). Knockout mice promote somatic cell reprogramming and higher litter size at birth (PubMed:29593216). Apparent retained intron. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay. Belongs to the peptidase M14 family. Truncated N-terminus.