Cholesterol mediates the function of the G protein-coupled receptor, rhodopsin, by reducing acyl chain packing free volume rather than interacting specifically with rhodopsin. Niu SL, Mitchell DC, Litman BJ. Manipulation of cholesterol levels in rod disk membranes by methyl-beta-cyclodextrin: effects on receptor activation. J Biol Chem 2002 Jun 7;277(23):20139-45.

   The level of metarhodopsin II (MII) formation was a function of phospholipid acyl-chain unsaturation, with the highest levels seen in DHA-containing bilayers. Similarly, the rate of coupling of MII to the retinal G protein, Gt, to form a MII-Gt complex, was enhanced in DHA bilayers relative to less unsaturated phospholipids. Visual and cognitive deficits observed in n-3 deficiency may result from decreased efficiency in related neurotransmitter and visual signaling pathways in the absence of DHA. Litman BJ, Niu SL, Polozova A, Mitchell DC. The role of docosahexaenoic acid containing phospholipids in modulating G protein-coupled signaling pathways: visual transduction. J Mol Neurosci 2001 Apr-Jun;16(2-3):237-42; discussion 279-84
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