The role of scavenger receptor BI in hepatitis - eTheses Repository ...

1.5 Lipoproteins
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Since 1992 there has been a steady accumulation of evidence implicating
lipoprotein metabolism in the HCV life cycle, specifically during viral entry, via
receptors such as SR-BI and the subsequent secretion of particles from
infected cells (25, 109, 312). Therefore prior to discussing these matters, the
following section will give an overview on the structure, physiological
importance and metabolism of lipoproteins. The majority of the material
covered is summarised from Lipoproteins in Health and Disease by Betteridge
et. al. (32) and Biochemistry of Lipids, Lipoproteins and Membranes by Vance
et. al. (321).
Lipids play an essential role in the maintenance of the human body, however
they are by their very nature insoluble in water, making their transport
problematic. Specific tissues overcome this by complexing them with proteins
into organised soluble structures known as lipoproteins, which circulate in the
plasma. Although diverse in nature, all lipoproteins have the same basic
structure; a core of neutral, therefore hydrophobic, triglycerides (TG) and
cholesterol esters, surrounded by a monolayer of polar phospholipids. The
protein component of these structures, termed apoproteins, sit in the
monolayer penetrating the central core to varying degrees. Whilst in the
circulation, these apoproteins determine the interaction of lipoproteins with the
mediators of their metabolism (Figure 1-3).