Metabolomics and Proteomics by LC-MS, GC-MS, and FT-MS
~Analyses of Detergent-Insoluble Complexes in Arabidopsis thaliana~

Abstract

Detergent-insoluble glycolipid-enriched complex (DIG) is the term to explain a putative membrane subdomain formed through lateral association of sphingolipids and cholesterol. In mammals and yeast, particular proteins such as GPI-anchored proteins, ion channels, and membrane receptors are localized to DIGs via specific sorting pathways. Thus, it is believed that DIGs serve as the functional sites for membrane trafficking, cell polarity, signaling, and cell-to-cell communication. Here, we examined whether or not such membrane subdomains are present in plant cells, and ask physiological roles, if any, of such DIGs in plants with the aid of proteomic approaches. We isolated and characterized DIG-components from Arabidopsis. GC-MS and LC-MS analyses demonstrated distinct compositions of sterols and fatty acids in the DIGs. Also, DIG-specific proteins were identified by 2D-PAGE, and the primary structures were determined using MALDI-FT-ICRMS.