GLYCOLIPID BIOSYNTHESIS - BIOSYNTHESIS OF MANNOSE- AND FUCOSE-CONTAINING GLYCOLIPIDS BY HELA CELLS

1. 1. Triton X-100 extracts of HeLa cells incorporated both [14C]fucose and [14C]mannose into endogenous glycolipid acceptors using GDP-[14C]fucose or GDP-[14C]mannose as substrates. 2. 2. Both systems had an optimum temperature of 37° and required Mg2+. 3. 3. Silicic acid-impregnated paper chromatography of the reaction products indicated that with each sugar a distinct glycolipid was synthesized. 4. 4. The [14C]fucose system exhibited a Km of 1.9 μM with respect to GDP-fucose, and the [14C]mannose system had a Km of 3.5 μM with respect to GDP-mannose. 5. 5. Using acetone precipitation it was possible to dissociate the enzyme and acceptor for each system. 6. 6. In each example the glycolipids synthesized were identified as glyco-glycerolipids and not sphingolipids or phospholipids. 7. 7. Diolein acted as an exogenous acceptor in the mannose system, while dipalmitin acted as an acceptor for the fucose system; distearin did not act as an acceptor for either sugar. © 1969.