α-N-acetylgalactosaminidase (nagalase)

α-N-acetylgalactosaminidase, commonly known as nagalase, is a glycoside hydrolase enzyme (EC 3.2.1.49) encoded by the human NAGA gene that catalyzes the removal of N-acetylgalactosamine residues from glycoproteins, primarily functioning in lysosomes to recycle glycoconjugates. In pathological conditions, tumor cells and virus-infected cells (e.g., HIV, influenza) secrete elevated levels of nagalase into serum, where it deglycosylates the vitamin D3-binding protein (Gc protein), preventing its conversion to macrophage activating factor (GcMAF) and thereby suppressing innate immunity through macrophage inactivation. This immune evasion mechanism correlates directly with tumor burden, cancer aggressiveness, metastasis, and viral persistence, with nagalase activity serving as a sensitive biomarker that drops rapidly post-tumor resection or effective therapy due to its short half-life. Deficiencies from NAGA mutations cause Schindler disease, a rare lysosomal storage disorder with neurological symptoms from undegraded substrates. While nagalase testing monitors cancer and infections, therapeutic strategies like GcMAF aim to restore immune activation, though they remain experimental.

Other names

alpha-N-acetylgalactosaminidaseα-NAGAalpha-NaGalaseN-acetylgalactosaminidase

GcMAF therapy bypasses nagalase-mediated deglycosylation to activate macrophages for antitumor and antiviral activity