Fig. 3.

Reconstitution of functional transmembrane proteins in lipid sponge droplets. (A) Cytochrome c oxidase (CcO) reaction. Addition of ferrocytochrome c to a droplet dispersion containing CcO leads to a gradual decrease in the absorbance at 550 nm, indicating the formation of ferricytochrome c. Alexa Fluor 488-labeled CcO partitions into the droplets. (Scale bar, 10 µm.) (B) E. coli diacylglycerol kinase (DAGK) reaction in droplets. DAGK is expressed in PURE system in the presence of droplets containing the substrate 1-decanoyl-rac-glycerol. Selective ion monitoring (SIM) chromatogram shows transformation to the phosphorylated product. Similarly expressed fluorescent fusion protein sfGFP-DAGK partitions into the droplets. (Scale bar, 5 µm.)