NTAN1 (N-terminal asparagine amidase) is a cysteine hydrolase that catalyzes the deamidation of N-terminal asparagine residues to aspartate 1, a critical step in the N-end rule protein degradation pathway 2. The enzyme specifically recognizes and acts only on N-terminal asparagine residues, preferring substrates with hydrophobic second-position residues 1. This modification renders proteins susceptible to arginylation, polyubiquitination, and proteasomal degradation 3, enabling selective protein turnover based on N-terminal identity. NTAN1 functions within a multiprotein targeting complex with arginyltransferase ATE1 and E3 ubiquitin ligases UBR1/UBR2, potentially enabling substrate channeling through sequential modifications 3. The enzyme is broadly expressed across developmental stages and adult tissues, with transcript-dependent specificities in perineural glia and neurons 4. Clinically, NTAN1 dysfunction is implicated in developmental disorders; duplications of chromosome 16.11 containing NTAN1 are associated with congenital heart disease and laterality defects 5, while 16p13.1 copy number variants show significant association with schizophrenia 6. Additionally, NTAN1 has been identified in genomic regions under positive selection during dog domestication, suggesting roles in neurobehavioral functions 7.