Fig. 1.

Structural analysis of D79 and S80 particles. (A) Native PAGGE (8–25%) of D79 (lane 1) and S80 (lane 3) particles. An 8–25% SDS/PAGGE analysis of cross-linked S80 after separation into monomeric (lane 5) and dimeric (lane 6) forms by gel filtration chromatography is also shown. Cross-linking was carried out at a 1:10 molar ratio of apoA-I: BS³ at 1 mg/ml apoA-I concentration. All gels were stained with Coomassie blue. (B and C) Negative stain electron micrographs of D79 and S80 particles. (Scale bars: 50 nm.) (D) Experimental cross-links compatible with 5/5 molecular registry of the double-belt model are shown as solid lines. The apoA-I molecules have been drawn as if they have been peeled off the edge of an HDL disk and laid flat. Cross-links in black are common to both D79 and S80 particles; those in blue are found in D79 only and those in gray are found in S80 only. Putative apoA-I helical segments are numbered according to Roberts et al. (31). Locations of the 21 Lys residues in apoA-I are identified as orange dots. All experimental cross-links found in D79 and S80 are listed in Table S1.