Figure 3.

Molecular model of lipid free apoA-I tetramer. The figure shows a cartoon representation of a lipid free apoA-I tetramer model constructed from two models of lipid free apoA-I dimer shown in Figure 2C, right (based on Segrest et al. lipid free apoA-I monomer, Figure 2C, left; Segrest et al., 2014). The protein chains are colored with gradient red/blue/cyan/magenta (N_t is colored with solid color and C_t with faded color). The K₈₈–K₁₁₈ MS-crosslink reported by Pollard et al. (2013) at a concentration of apoA-I of 1 mg/mL may come from a tetrameric state of apoA-I. In this hypothetical tetramer model of lipid free apoA-I, the distance between K_88A and K_118C is 10.6 Å and between K_88C and K_118A is 9.6 Å.