LIPID Arrays: New Tools in the Understanding of Membrane Dynamics and Lipid Signaling

Polyphosphoinositides. Stimulation of RAW 264.7 cells with zymosan led to elevated PI-monophosphate (PIP) and PI-bisphosphate (PIP₂) levels (top panel) compared to basal (lower panel). 3 × 10⁶ cells were challenged with 50 μg/ml zymosan (a protein-carbohydrate complex derived from yeast cell wall) for 15 minutes followed by aspiration and pelleting. Inositides were then extracted using a modified Bligh/Dyer extraction procedure (51). Mass spectral analysis was performed on a Finnigan TSQ Quantum triple quadrupole mass spectrometer (ThermoFinnigan, San Jose, CA) equipped with a Harvard Apparatus syringe pump and an electrospray source. Samples were analyzed at an infusion rate of 10 μl/min in negative mode over the range of m/z 400 to 1100.