Scientists have discovered a new cellular pathway that controls synthesis of a well-known sugar. The research, published online this week in Nature Chemical Biology, has global implications for cell biology due to the large number of roles for the sugar.
The sugar, CD15 antigen, or Lewis x (Le), is typically found on the cell surface and is important in both the immune system and in cell differentiation. Until now, it was believed that, when needed on the cell surface, it was synthesized from scratch by machinery inside the cell and then sent to the surface.
Robert Sackstein and Samah Zeineb Gadhoum show that a related sugar structure, sialyl-CD15, which carries an extra molecule called sialic acid and is also present on the cell surface, is directly changed to CD15. This shows that sialyl-CD15 serves partly as a storehouse for CD15. This surprising new route means that scientists will need to rethink how CD15 and sialic acid control cell function.