Lipoprotein(a) the Insurgent: A New Insight into the Structure, Function, Metabolism, Pathogenicity, and Medications Affecting Lipoprotein(a) Molecule

Figure 1

Lp(a) structure, composition, and physicochemical properties. A—Lp(a) is composed of apo-B100 covalently fastened together with apo(a), which originates from kringle IV (KIV) and KV, and the inactive protease domain of PLG. Apo(a) has important differences compared with PLG. (1) Apo(a) has an unpaired cysteine and forms a disulfide bond with apoB to generate the lipoprotein particle Lp(a). (2) Apo(a) has an inactive protease domain. (3) Apo(a) includes 10 subtypes of KIV repeats, composed of 1 copy each of KIV1, multiple copies of KIV2, and 1 copy of KIV310, KV, and an inactive protease-like domain. (4) Apo(a) lacks kringles 1–3 of PLG but has kringles 5 and 10 of KIV, of which KIV₂ is present in numerous repeats. OxPLs exist covalently bonded to the apo(a) component and are suspended in the lipid phase of apo-B100. B—Comparison between Lp(a) and LDL with regard to their composition and physicochemical properties.