Using mammalian gene-overexpression system, in vitro catalytic activities of CMP-NeuAc:Galβ1→4GlcNAc α2→6sialyltransferase on glycosphingolipid acceptors were analyzed. We transfected the mammalian expression vector containing the cDNA that was cloned from Daudi cells into COS-1 cells, and selected monoclonal transfectants in the presence of G418. Although the transfectedα2→6sialyltransferase can catalyze NeuAc transfer onto glycoprotein acceptors more than glycolipids based on kinetic analyses, the substantial synthesis of IV6NeuAc-nLcOse4Cer was observed and the activities were 7-to 9-times higher in the transfected cells than in the mock transfectants. In addition, the transfected COS-1 cells with α2→6sialyltransferase cDNA were revealed to contain a higher amount of ganglioside that has the terminal NeuAcα2→6Gal sequence in the in situ situation than the mock transfectants. These results using transfectants, together with those using the purified enzyme protein, suggest that the α2→6sialyltransferase enzyme from Daudi cells can also catalyze NeuAc transfer in α2→6 linkage onto glycosphingolipid acceptors.
|Number of pages||12|
|Journal||Journal of Lipid Research|
|Publication status||Published - 09-1997|
All Science Journal Classification (ASJC) codes
- Cell Biology