Both HDLs and their major protein constituent apolipoprotein A-I (apoA-I) are transported through aortic endothelial cells. The knock-down of the ATP-binding cassette transporters A1 (ABCA1), G1 (ABCG1), and of the scavenger receptor-BI (SR-BI) diminishes but does not completely block the transport of apoA-I or HDL, so that other receptors appear to be involved. The ectopic β-chain of F₀F₁ ATPase has been previously characterized as an apoA-I receptor, triggering HDL internalization in hepatocytes.

The ectopic presence of the β-chain of F₀F₁ ATPase on the surface of endothelial cells was confirmed by cell surface biotinylation. RNA-interference and the F₀F₁ ATPase inhibitory peptide IF₁ reduced cell binding of apoA-I but not HDL, as well as association and transendothelial transport of both apoA-I and HDL. Furthermore, apoA-I stimulated F₀F₁ ATPase catalyzed ATP hydrolysis. The generated ADP as well as apoA-I stimulated the binding, cell association, and internalization of HDL. Both in the presence and absence of ADP inhibition of the purinergic receptor P2Y₁₂ but not P2Y₁ decreased the cell association of apoA-I and HDL. Coinhibition of β-ATPase and ABCA1 had no additive effects on the cell association and transport of apoA-I. Reduced cell association of HDL by β-ATPase inhibition was not further decreased by additional knock-down of ABCG1 or SR-BI.

Binding of apoA-I to ectopic F₀F₁ ATPase triggers the generation of ADP, which via activation of the purinergic receptor P2Y₁₂ stimulates the uptake and transport of HDL and initially lipid-free apoA-I by endothelial cells.