A biochemical characterization of the plasma membrane of the myxamoeba and swarm cells of the myxomycete Didymium iridis

Abstract

The plasma membrane of the myxamoeba and warm cells of the Myxomycete Didymium iridis was biochemically characterized. Analysis of membrane proteins by SDS-polyacrylamide gel electrophoresis stained with Coomassie Blue revealed twelve components ranging in molecular weight from 24,000-200,000. The two slowest migrating components were also stained by the periodic acid - Schiffs (PAS) procedure indicating the presence of glycoproteins (GP) in these bands.

The lipid component was separated into major classes by column chromatography and further fractionated by thin-layer chromatography. Fivephospholipids were resolved. Although two remain unidentified, it appears that phosphatidyl choline (PC), phosphatidyl ethanolamine (PE), and phosphatidyl insitol (PI) are present while the lone glycolipid resolved is a derivative of monogalactosyldiacylglycerol. The membrane neutral lipid is present as sterol esters as shown by gas-liquid chromatography and infrared spectroscopy. The sterols most likely to be present include cholestranol, stigmasterol, and ergasterol.