Fig 4. Sialylated mucins are included in lipid rafts whereas TS is not.

(A) Cold Triton X-100 partition. Sialylated trypomastigotes were lysed at 4°C. Mucins were predominantly recovered in the pellet whereas TS and HSP70, a cytosolic protein, were recovered in the supernatant. (B) Triton X-114 extraction for GPI-anchored proteins. Parasites were lysed at 4°C and detergent and aqueous phases separated at 37°C and analyzed by Western blots. Mucins and TS partitioned in the detergent phase due to their GPI-anchoring. Glutamate Dehydrogenase, a cytosolic protein, was recovered in the aqueous phase. (C) Purification of DRMs by step-gradient ultracentrifugation. Trypomastigotes were lysed in Triton X-100 at 4°C or 37°C and centrifuged in an Optiprep gradient. Mucins floated to the 35%-5% interface (lane 6) only when lysis was done at 4°C indicating its DRM nature in contrast to TS. (D) Living parasites were sialylated from a Neu5Az donor, then treated for membrane fluidization with 1% diethyl ether in phosphate-buffered saline (PBS) and fixed with p-formaldehyde (PFA). Doted labeling for TS and mucins was disrupted only after 90sec treatment even showing colocalization.