SIALYLTRANSFERASE - A NOVEL ACUTE-PHASE REACTANT

1. Proteins that are released into the circulation in elevated amounts in injured mammals are referred to as acute-phase reactants. Most are liver synthesized glycoproteins of the secretable type. However, -bet a(1-->4)-GlcNAc-alpha(2-->6)-sialyltransferase (EC 2.4.99.1) is a nove l acute-phase reactant since it is a Golgi membrane-bound enzyme rathe r than a secretable glycoprotein. 2. The role of glucocorticoids and c ytokines in the control of synthesis and expression of acute-phase gly coproteins, including sialyltransferase, is discussed. 3. The acute-ph ase behaviour of -beta(1-->4)-GlcNAc-alpha(2-->6)-sialyltransferase is dependent on the release of the enzyme from the Golgi in the acute-ph ase state. The mechanism of release of a catalytically active form of the enzyme is described.