Glyco-Forum section Letters to the Glyco-Forum Systematic nomenclature for sialyltransferases

Sialyltransferases are a family of glycosyltransferases that transfer sialic acid from the donor substrate CMP-sialic acid to acceptor oligosaccharide substrates (Paulson and Colley, 1989). Successful efforts to clone the cDNAs of this family of enzymes have revealed a homologous gene family that is larger than previously recognized. The present nomenclature for dis-tinguishing the various sialyltransferases is inadequate to un-ambiguously distinguish one enzyme from another, particu-larly when multiple names often exist in the literature to de-scribe the same enzyme. Accordingly, we propose a systematic nomenclature similar to that used in describing other glycos-yltransferase families (e.g., N-acetyl glucosaminyl- and fuco-syl-transferases). Some additional features of this nomencla-ture may be of value in developing a systematic nomenclature for other glycosyltransferase families. At least 13 distinct sialyltransferase cDNAs have been cloned (Table I) using various approaches. These include clon-ing of the enzymes using information derived from the peptide sequence of the purified protein. The cloning of the cDNA was also achieved by expression cloning using the antibodies gen-erated against the purified enzymes. However, these strategies have proven laborious for cloning of sialyltransferases due to the low abundance of these enzymes in tissues, thus resulting in difficulty of their purification. Nonetheless, six distinct si-alyltransferases have been purified to homogeneity (Sadler e