Glycosylphosphatidylinositol-anchored protein chips for patient–tailored multi–parameter proteomics

Inhibition of lipolysis by palmitate, H2O2, and the antidiabetic sulfonylurea drug, glimepiride, in rat adipocytes has been shown previously to rely on the concerted degradation of cAMP by the glycosylphosphatidylinositol (GPI)-anchored phosphodiesterase Gce1 and 5-nucleotidase CD73, which both gain access to the lipid droplets (LDs). The present report demonstrates the translocation of Gce1 and CD73, harboring the intact GPI anchor, from detergent-insoluble glycolipid-enriched plasma membrane domains (DIGs) to the LDs in response to palmitate, H2O2, and glimepiride by analysis of their steady-state distribution using photoaffinity labeling and activity determination as well as of their redis-tribution after pulse or equilibrium metabolic labeling. We were surprised to find that palmitate, H2O2, and glimepirid