Publisher Summary This chapter provides a comprehensive overview of the current state of knowledge of the research with particular emphasis on evolving concepts of fatty acid binding proteins (FABP) structure, regulation, and function. Long-chain fatty acids provide the main energy source of most mammalian tissues and also comprise essential components of the structural lipids of cell membranes. The purification of the specific proteins responsible for the low-molecular-weight fatty-acid binding protein activity in different tissues leads to the characterization of three structurally distinct FABP of similar size, each the product of a separate gene. The three cytosolic FABP are generally named according to their tissues of greatest abundance, and comprise liver FABP, intestinal FABP, and heart muscle FABP. A role for the 40-kDa LPM-FABP as a specific cell membrane carrier in the transport of long chain fatty acids into the cells of the liver and possibly other tissues as well is available. The 14- to 15-kDa cytosolic FABPs may function as intracellular acceptors and carriers of long-chain fatty acids and their coenzyme A (CoA) esters, maintaining the ability of the tissues, particularly liver, intestine, heart, and skeletal muscle to utilize fatty acids over wide and acutely varying ranges of flux.

The cellular fatty acid binding proteins: aspects of structure, regulation, and function.

https://www.jbc.org/content/262/33/16060.full.pdf

The human and rodent intestinal fatty acid binding protein genes. A comparative analysis of their structure, expression, and linkage relationships.

The mechanism by which fatty acids enter cardiomyocytes is unclear. Therefore, the influx kinetics of [3H]oleate into isolated rat heart myocytes were examined. Cells were incubated at 37 degrees C with [3H]oleate bound to albumin in various molar ratios and the initial rate of uptake (V0) was determined as a function of the unbound oleate concentration in the medium. V0 was saturable with increasing oleate concentrations incubated (Km 78 nM; Vmax 1.9 nmol X min-1 per 10(6) cells) and temperature dependent with an optimum at 37 degrees C. Furthermore, binding of [3H]oleate to isolated plasma membranes of cardiomyocytes was saturable, revealing a KD of 42 nM, and was inhibited by heat denaturation or trypsin pretreatment of the membranes. From these membranes a single 40-kD protein with high affinity for a variety of long chain fatty acids was isolated. With a monospecific antibody to this membrane protein, binding as well as cellular influx of [3H]oleate was selectively inhibited. These data indicate that at least a portion of myocardial fatty acid uptake is mediated by a specific membrane protein.

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Fatty acid uptake by isolated rat heart myocytes represents a carrier-mediated transport process.

Analysis of the tissue-specific expression, developmental regulation, and linkage relationships of a rodent gene encoding heart fatty acid binding protein.

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Fatty acid binding protein from rat heart. The fatty acid binding proteins from rat heart and liver are different proteins.