Liver and intestinal fatty acid-binding proteins obtain fatty acids from phospholipid membranes by different mechanisms.

Intestinal enterocytes contain high concentrations of two cytosolic fatty acid-binding proteins (FABP), liver FABP (L-FABP) and intestinal FABP (I-FABP), which are hypothesized to play a role in cellular fatty acid trafficking. The mechanism(s) by which fatty acids move from membranes to each of these proteins is not known. Here we demonstrate that fluorescent anthroyloxy fatty acid analogues (AOFA) are transferred from phospholipid vesicles to L-FABP versus I-FABP by different mechanisms. For L-FABP a diffusion-mediated transfer process is demonstrated. The AOFA transfer rate from phosphatidylcholine-containing vesicles (POPC) to L-FABP is similar to that observed with another diffusional process, namely inter-membrane AOFA transfer. Furthermore, the AOFA transfer rate was modulated by buffer ionic strength and AOFA solubility, while the transfer rate remained relatively unchanged by the presence of anionic phospholipids in vesicles. In contrast, the data for I-FABP suggest that a transient collisional interaction of I-FABP with the phospholipid membrane occurs during AOFA extraction from the vesicles by the protein. In particular, the presence of the anionic phospholipid cardiolipin in donor vesicles increased the rate of AOFA transfer to I-FABP by 15-fold compared with transfer to POPC vesicles. The effects of ionic strength on transfer suggest that the interaction of I-FABP with cardiolipin-containing vesicles is likely to contain an electrostatic component. Finally, based on the regulation of AOFA transfer to I-FABP compared with transfer from I-FABP, it is hypothesized that apo- and holo-I-FABPs adopt conformations which may differentially promote I-FABP-membrane interactions. In summary, the results suggest that I-FABP, but not L-FABP, can directly extract fatty acids from membranes, supporting the concept that I-FABP may increase the cytosolic flux of fatty acids via intermembrane transfer.

[1]  J. Sambrook,et al.  Molecular Cloning: A Laboratory Manual , 2001 .

[2]  J. Storch,et al.  The fatty acid transport function of fatty acid-binding proteins. , 2000, Biochimica et biophysica acta.

[3]  D. Cistola,et al.  The helical domain of intestinal fatty acid binding protein is critical for collisional transfer of fatty acids to phospholipid membranes. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[4]  G. J. van der Vusse,et al.  Modelling intracellular fatty acid transport: possible mechanistic role of cytoplasmic fatty acid-binding protein. , 1997, Prostaglandins, leukotrienes, and essential fatty acids.

[5]  J. B. Massey,et al.  Spontaneous transfer of monoacyl amphiphiles between lipid and protein surfaces. , 1997, Biophysical journal.

[6]  M. Hodsdon,et al.  Ligand binding alters the backbone mobility of intestinal fatty acid-binding protein as monitored by 15N NMR relaxation and 1H exchange. , 1997, Biochemistry.

[7]  M. Hodsdon,et al.  Discrete backbone disorder in the nuclear magnetic resonance structure of apo intestinal fatty acid-binding protein: implications for the mechanism of ligand entry. , 1997, Biochemistry.

[8]  Elizabeth R. Smith,et al.  The role of membranes and intracellular binding proteins in cytoplasmic transport of hydrophobic molecules: Fatty acid-binding proteins , 1996 .

[9]  G. J. van der Vusse,et al.  Cellular fatty acid-binding proteins: their function and physiological significance. , 1996, Progress in lipid research.

[10]  J. Storch,et al.  Fatty Acid Transfer from Liver and Intestinal Fatty Acid-binding Proteins to Membranes Occurs by Different Mechanisms* , 1996, The Journal of Biological Chemistry.

[11]  J. Storch,et al.  Role of portal region lysine residues in electrostatic interactions between heart fatty acid binding protein and phospholipid membranes. , 1996, Biochemistry.

[12]  A. Kleinfeld,et al.  Equilibrium constants for the binding of fatty acids with fatty acid-binding proteins from adipocyte, intestine, heart, and liver measured with the fluorescent probe ADIFAB. , 1994, The Journal of biological chemistry.

[13]  J. Storch,et al.  Regulation of fluorescent fatty acid transfer from adipocyte and heart fatty acid binding proteins by acceptor membrane lipid composition and structure. , 1994, The Journal of biological chemistry.

[14]  F. Schroeder,et al.  Recombinant liver fatty acid binding protein interacts with fatty acyl-coenzyme A. , 1994, Biochemistry.

[15]  J. Gordon,et al.  Rat intestinal fatty acid binding protein. A model system for analyzing the forces that can bind fatty acids to proteins. , 1993, The Journal of biological chemistry.

[16]  A. Kleinfeld,et al.  Interactions of long-chain fatty acids and albumin: determination of free fatty acid levels using the fluorescent probe ADIFAB. , 1993, Biochemistry.

[17]  J. Sunderland,et al.  Effect of phospholipid headgroup composition on the transfer of fluorescent long-chain free fatty acids between membranes. , 1993, Biochimica et biophysica acta.

[18]  G. J. van der Vusse,et al.  On the mechanism of long chain fatty acid transport in cardiomyocytes as facilitated by cytoplasmic fatty acid-binding protein. , 1993, Journal of theoretical biology.

[19]  A. Kleinfeld,et al.  A fluorescently labeled intestinal fatty acid binding protein. Interactions with fatty acids and its use in monitoring free fatty acids. , 1992, The Journal of biological chemistry.

[20]  Hyung-Gu Kim,et al.  Mechanism of free fatty acid transfer from rat heart fatty acid-binding protein to phospholipid membranes. Evidence for a collisional process. , 1992, The Journal of biological chemistry.

[21]  J. Storch,et al.  Free fatty acid transfer from rat liver fatty acid-binding protein to phospholipid vesicles. Effect of ligand and solution properties. , 1992, The Journal of biological chemistry.

[22]  J. Storch.  Mechanism for binding of fatty acids to hepatocyte plasma membranes: Different interpretation , 1990, Hepatology.

[23]  J. Storch,et al.  Transfer of fluorescent fatty acids from liver and heart fatty acid-binding proteins to model membranes. , 1990, The Journal of biological chemistry.

[24]  F. Spener,et al.  Compartmentation of hepatic fatty-acid-binding protein in liver cells and its effect on microsomal phosphatidic acid biosynthesis. , 1989, Biological chemistry Hoppe-Seyler.

[25]  A. Kleinfeld,et al.  Transfer of long-chain fluorescent free fatty acids between unilamellar vesicles. , 1986, Biochemistry.

[26]  N. Bass.  Function and regulation of hepatic and intestinal fatty acid binding proteins. , 1985, Chemistry and physics of lipids.

[27]  J. Veerkamp,et al.  A radiochemical procedure for the assay of fatty acid binding by proteins. , 1983, Analytical biochemistry.

[28]  S. Charlton,et al.  Kinetics of transfer of pyrene and rac-1-oleyl-2-[4-(3-pyrenyl)butanoyl]glycerol between human plasma lipoproteins. , 1982, Biochemistry.

[29]  B. Ketterer,et al.  The influence of soluble binding proteins on lipophile transport and metabolism in hepatocytes. , 1981, The Biochemical journal.

[30]  C. H. Walker.  The Hydrophobic Effect: Formation of Micelles and Biological Membranes , 1981 .

[31]  T. E. Thompson,et al.  Mechanism of the spontaneous transfer of phospholipids between bilayers. , 1980, Biochemistry.

[32]  L. Thilo.  Kinetics of phospholipid exchange between bilayer membranes. , 1977, Biochimica et biophysica acta.

[33]  M. M. Bradford.  A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. , 1976, Analytical biochemistry.

[34]  U. K. Laemmli,et al.  Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4 , 1970, Nature.

[35]  M. Polanyi,et al.  The Theory of Rate Processes , 1942, Nature.

[36]  J. Veerkamp,et al.  Cytoplasmic fatty acid-binding proteins: their structure and genes. , 1995, Progress in lipid research.

[37]  T. A. Jones,et al.  Lipid-binding proteins: a family of fatty acid and retinoid transport proteins. , 1994, Advances in protein chemistry.

[38]  P. Henkart,et al.  Fluidity of cell membranes--current concepts and trends. , 1979, International review of cytology.

[39]  T. E. Thompson,et al.  Preparation of homogeneous, single-walled phosphatidylcholine vesicles. , 1974, Methods in enzymology.

[40]  T. E. Thompson,et al.  [45] Preparation of homogeneous, single-walled phosphatidylcholine vesicles☆ , 1974 .

[41]  G. Gomori.  A modification of the colorimetric phosphorus determination for use with the photoelectric colorimeter. , 1942 .