Lipid-binding proteins physiological functions

Glatz, J. E, and van der Vusse, G. J. 1996. Cellular fatty acid binding proteins Their function and physiological significance. Progress in Lipid Research 3 243-282. 

The EFA metabolism is presented in several extensive reviews.9 16 17 Much of the information concerning EFA physiology and biochemistry has been derived from work in hepatocytes and may be of limited relevance to epidermis since a major role of the liver is to convert dietary lipids into energy stores. Meanwhile, keratinocytes are involved in the fatty acid metabolism required both for normal cellular processes and the specialized role in the permeability barrier. Unlike the liver, the epidermis does not possess the capacity to desaturate at the A5 or A6 position, and therefore the skin relies on a supply of AA, LA, and ALA from the bloodstream. There is evidence for a distinct fatty acid binding protein in keratinocyte plasma membranes that is involved in EFA uptake into the skin and also recycling of free fatty acids from the stratum corneum.18 The transport mechanism in epidermis differs from that in hepatocytes since there is preferential uptake of LA over OA, which may function to ensure adequate capture of LA for barrier lipid synthesis.18... 

Most lipid-soluble hormones in the blood are bound to specialized carrier proteins. The availability of hormones for physiological functions depends on the total concentration of the hormone as well as the amount of hormone existing in the free state protein-bound hormones are not readily available for receptor binding. While lack of carrier proteins could impair the transport of hormones to target organs, excessive amounts may decrease the availability of free hormones. 

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