Recombinant Human ST8SIA6 Protein, CF

Polysialic acid (PSA), a glycan abundant on the neural cell adhesion molecule (NCAM) during embryonic development, negatively modulates the adhesive properties of NCAM (1). Following birth, PSA expression decreases promptly and becomes restricted to the hippocampus, hypothalamus, and olfactory bulb-areas of the brain that require continuous cell migration and synaptic plasticity (2). Expression of PSA in cancer cells has been suggested to increase tumor invasiveness and promote tumor growth (3). However; the mouse St8sia6 only has alpha-2,8 sialyltransferase activity toward both glycolipids and glycoproteins that has the NeuAc-alpha -2,3(6)-beta -D-Gal sequence at the nonreducing ends of their carbohydrate groups, and forms NeuAc-alpha -2,8-NeuAc structures, but not oligosialic or polysialic acid structures (4). Like most glycosyltransferases, ST8SIA6 may be a Golgi‑resident type II membrane protein. It is expressed in various tissues at low levels but is highly expressed in breast cancer and Dami megakaryocyte cell lines (5). The activity of this enzyme has been measured with a phosphatase-coupled method (6).