Fig. 4.

Representative AFM images of phase separated DPPC/DPPS/chol bilayers after incubation with 0.05 to 1.0 μg/ml Hsp70-1A. The Lo and Ld phases are labeled for ease of distinction. Hsp70-1A selectively parted into the Lo phase and formed circular clusters with increasing protein density towards the center of a cluster. With increasing concentration, cluster size and packing density of molecules grew. a Hsp70-1A concentration of 0.05 μg/ml. b Protein concentration of 0.25 μg/ml. The inset shows the corresponding overview scan, and the dashed square marks the area of the zoom-in. c At a concentration of 0.5 μg/ml, clusters started to bulge out of plane and formed blebs. The inset shows a magnification of one of the blebs. d Hsp70-1A concentration of 0.75 μg/ml. At higher concentration, membrane blebs became prone to rupturing. e Hsp70-1A concentration of 1.0 μg/ml. The bottom panel shows a 20 × 20-μm² overview scan. Numerous membrane blebs had formed and many of them had burst, leaving holes that were filled with protein as illustrated by the zoom-in in the top panel and the magnification of a hole in the inset image