Figure 3. SAA forms complexes with hydrolyzed model or plasma lipids.

(A) SAA was incubated with either unmodified POPC to form SAA-POPC complexes or with hydrolyzed POPC to form SAA + hydPOPC complexes (see 'Materials and methods' for details). Protein:POPC molar ratios were 1:1, 1:10 or 1:100 as indicated; sPLA₂-III or sPLA₂-IIa was used as indicated. (B, C) Human plasma lipoproteins including HDL (B) and LDL (C) were hydrolyzed with sPLA₂ group-III or -IIa to form hydHDL or hydLDL, respectively. In samples marked SAA + hydLDL (B) or hydHDL (C), the hydrolyzed lipoproteins were incubated with SAA using protein weight ratios of 1:1 SAA:apoA-I (for HDL) or 1:1 SAA:apoB (for LDL) as described in 'Materials and methods'. Similar incubation mixtures of SAA with non-hydrolyzed HDL (SAA+HDL) or LDL (SAA+LDL) are shown for comparison. Figure 3—figure supplement 1 shows non-denaturing PAGE that monitors the remodeling of SAA-containing model and plasma lipoproteins upon their hydrolysis by sPLA₂.

Figure 3—figure supplement 1. Non-denaturing PAGE monitors remodeling of SAA-containing model and plasma lipoproteins upon their hydrolysis by sPLA₂.

(A) SAA-POPC complexes were prepared by incubating SAA with POPC SUV using SAA:POPC molar ratios of 1:1, 1:10 or 1:100 (indicated in the lanes). Lanes for intact SAA-POPC particles are shown, as well as those for similar particles that have been hydrolyzed with sPLA₂-III or sPLA₂-IIa. (B) Native HDL and HDL that have been enriched with exogenous SAA using an SAA:apoA-I molar ratio of 1:4 (SAA-HDL) hydrolyzed by sPLA₂-III or sPLA₂-Ila (as indicated on the lanes). Non-hydrolyzed native HDL (nHDL), SAA-HDL and lipid-free SAA were used as controls.