Regulation of membrane-bound enzymes of glycosphingolipid biosynthesis

The descriptive phase of glycosphingolipid biochemistry has blossomed over the past decade with the application of exquisitely sensitive analytical methods of mass spectrometry, NMR, and monoclonal antibody technology. Consequently, appreciation of the interrelation among the complex carbohydrate structures that are expressed on the cell surface has focused attention on the regulation of the glycosyltransferases responsible for such diversity. This review explores some aspects of several potential molecular mechanisms of regulation--compartmentation of glycosyltransferases and effect of the immediate lipid environment; modulation of enzyme activity by acceptor substrate, divalent cations, and availability of sugar nucleotides; modifications of the enzyme operon elicited by viral transformation integration sites, or to the enzyme by phosphorylation-dephosphorylation--which are presently at the cutting edge of glycosphingolipid science.