Beta-1,4-N-Acetyl Galactosaminyl Transferase 1 (b4GALNT1)

The G(M2) and G(D2) gangliosides are sialic acid-containing glycosphingolipids involved in signal transduction and cell-cell recognition. Nagata et al. (1992) used expression cloning to isolate the cDNA encoding the enzyme responsible for generating G(M2) and G(D2) glycosphingolipids.

b4GALNT1 is termed beta-1,4-N-acetylgalactosaminyltransferase (GalNAcT) (EC 2.4.1.92), or G(M2)/G(D2) synthase. The cDNA encodes a 561-amino acid polypeptide. Northern blot analysis revealed that the gene is expressed as 2 differently sized transcripts in all cells tested that expressed G(MS), G(D2), or both. These findings indicate that the cDNAs catalyze the transfer of GalNAc into G(M3) and G(D3) by a beta-1,4 linkage, resulting in the synthesis of G(M2) and G(D2), respectively.