The interaction of lecithin-cholesterol acyltransferase (LCAT) with apolipoprotein A-I (apoA-I) plays a critical role in highdensity lipoprotein (HDL) maturation.Wepreviously identified a highly solvent-exposed apoA-I loop domain (Leu¹⁵⁹–Leu¹⁷⁰) in nascent HDL, the so-called “solar flare” (SF) region, and proposed that it serves as an LCAT docking site (Wu, Z., Wagner, M....