The chondroitin N-acetylgalactosaminyltransferase family includes Beta-1,4-GalNAc-T, Beta-1,4-GalNAc-T2, Beta-1,4-GalNAc-T3 and Beta-1,4-GalNAc-T4. The Beta-1,4-GalNAc-T protein consists of a short N-terminal residue, a transmembrane region and a long C-terminal residue, which includes a catalytic domain and localizes to the Golgi apparatus. Beta-1,4-GalNAc-T utilizes simple ganglioside GM3 as a substrate for more complex gangliosides GM2, GM1 and GD1a. Beta-1,4-GalNAc-T is expressed in normal brain tissues and in various malignant transformed cells, such as malignant melanoma, neuroblastoma and adult T cell leukemia. Mice lacking the Beta-1,4-GalNAc-T protein develop significant and progressive behavioral neuropathies, including deficits in reflexes, strength, coordination and balance. Beta-1,4-GalNAc-T is a potential molecular marker for detecting melanoma cells and monitoring tumor progression.