Picodiscs for facile protein-glycolipid interaction analysis.

Protein interactions with glycolipids are implicated in diverse cellular processes. However, the study of protein-glycolipid complexes remains a significant experimental challenge. Here, we describe a powerful new assay that combines electrospray ionization mass spectrometry (ESI-MS) and picodiscs, which are composed of human sphingolipid activator protein saposin A and a small number of phospholipids, to display glycolipids in a lipid environment for protein-glycolipid interaction studies in aqueous solution. Time-resolved measurements of enzyme catalyzed hydrolysis of glycolipid substrates and the detection of low, moderate, and high affinity protein-glycolipid interactions serve to demonstrate the reliability and versatility of the assay.