Which lipoprotein is prothrombotic and homologous to plasminogen due to its Apo B-100?

• A. IDL
• B. B-VLDL
• C. Lp(a)
• D. LpX

Answer: (C)

A lipoprotein can promote thrombosis not only by contributing to atherosclerosis but also by interfering with the body’s clot-dissolving system, plasminogen. Lp(a) is an LDL-like particle that carries Apo B-100 and has an extra protein, apolipoprotein(a), attached to Apo B-100. Apolipoprotein(a) contains kringle domains that resemble the structure of plasminogen, so it can mimic plasminogen. This structural similarity allows Lp(a) to compete with plasminogen for binding sites on fibrin and cell surfaces, reducing plasmin formation and fibrinolysis. The net effect is a prothrombotic state, on top of any atherogenic risk from the lipids.

Other lipoproteins lack this apo(a) component and the plasminogen-like domains, so they don’t have the same plasminogen-mimicking, fibrinolysis-inhibiting effect. Lipoprotein X and the typical remnant lipoproteins (IDL, β-VLDL) do not carry apolipoprotein(a) and thus don’t contribute to this specific prothrombotic mechanism.