Applicable Scientific Terms:
ABCA1 – ATP binding cassette transporter A1 is a plasma membrane protein that is responsible for transferring cellular cholesterol and phospholipid to lipid-poor apolipoprotein acceptors such as apoAI during the formation of nascent HDL.
ApoAI – Apolipoprotein AI is the major protein component of HDL. The presence of an amphipathic a-helical domain in apoAI is required for efficient phospholipid and cholesterol efflux, and the strong lipid-binding C-terminal a-helix in apoAI plays a key role in efflux.
Nascent HDL – poorly-lipidated Lipoprotein that are formed by the transfer of small amounts of cholesterol and phospholipid to apolipoprotein A-I resulting in oval/disc shaped complexes. In the peripheral tissues, nascent HDLs promote the efflux of cholesterol from tissues via ABCA1 mediated processes.
Mature HDL – are formed when sufficient lipid has been transferred to Nascent HDL to create spherical-shaped lipoproteins that contain lipids within the core. Mature HDLs also promote efflux from peripheral tissues, but through the actions of ABCG1.
Lipoproteins – complex structures which transport lipids, including cholesterol, in the blood. Their metabolism is closely interrelated with the initiation and progression of atherosclerosis. The two most abundant lipoproteins in the plasma are LDLs and HDLs.
Macrophages – inflammatory cells (“white” blood cells) derived from monocytes. In the blood vessel wall, uptake of lipid from modified lipoproteins into macrophages results in foam cell generation. The accumulation of foam cells leads to the formation of fatty streaks, considered to be the initial lesion leading to the development of complex atherosclerotic lesions.
Nuclear Receptor – Nuclear receptors are intracellular receptor proteins that bind to hydrophobic signal molecules (such as steroid and thyroid hormones) or intracellular metabolites and are thus activated to bind to specific DNA sequences, affecting transcription.
RCT – Reverse Cholesterol Transport: removal of cholesterol from the vascular wall, which is then transported by HDL to receptors in the liver, allowing cholesteral to be excreted from the human body (Steve… please review…)
SR-BI – Scavenger receptor class BI is a plasma membrane receptor that mediates the bi-directional movement of cholesterol between cells and mature lipoproteins (Mature HDL), as well as the selective uptake into cells of cholesterol ester from the core of mature lipoproteins.