The jelly layers and cortex of the unfertilized Xenopus laevis egg: carbohydrate, phospholipid and protein analysis

Differences in the carbohydrate composition were found in the jellies and the cortex of the unfertilized Xenopus laevis egg using lectins and blood group antibodies. Blood group H trisaccharide was detected in the outer jelly and "A-like" oligosaccharide was found in the inner jelly. The blood group A trisaccharide was detected in the vitelline envelope and the cortex. The plasma membranes were isolated and partially purified by differential centrifugation on sucrose cushion. The phospholipid composition of the membrane was assessed by quantitative two-dimensional thin layer chromatography. The major phospholipids were sphingomyelin (8%), phosphatidylcholine (55%), phosphatidylinositol and phosphatidylserine (7%), and phosphatidylethanolamine (26%). The external application of phospholipase A2 indicated a possible asymmetry of the phospholipids in the membrane such as the acidic phospholipids are preferentially located at the inner leaflet. The membrane protein and glycoprotein pattern was examined by gel electrophoresis using Triton and selective staining. Six major glycoproteins ranging from 250 to 32 kDa, were detected among the Triton-insoluble components.