Fig 3. Vpu fractionates with the water insoluble fraction and can be subsequently solubilized by detergents.

Whole cell lysates of E. coli BL21s expressing Vpu were fractionated into non- aqueous (lane 1) and aqueous (lane 2) fractions by centrifugation. The non-aqueous fraction (pellets) were resuspended in extraction buffer containing various detergents (1% final concentration): βDM (lane 3), βDDM (lane 4), CHAPS (lane 5), OG (lane 6), LDAO (lane 7) and DPC (lane 8). Following overnight incubation at 4°C, detergent-soluble proteins were separated from insoluble proteins by centrifugation and fractionated by SDS-PAGE followed by immunoblot analysis using a Vpu-specific antibody. Vpu is indicated by a black arrow.