Biochemical and biophysical analysis of the intracellular lipid binding proteins of adipocytes

  • Melanie A. Simpson
  • Vince J. LiCata
  • Natalie Ribarik Coe
  • David A. Bernlohr
Part of the Molecular and Cellular Biochemistry book series (DMCB, volume 29)


Adipocytes express two lipid-binding proteins; the major one termed the adipocyte lipid-binding protein or aP2 (ALBP/aP2) and a minor one referred to as the keratinocyte lipid-binding protein (KLBP). In order to evaluate the potential physiological roles for these proteins, their biochemical and biophysical properties have been analyzed and compared. ALBP/aP2 and KLBP exhibit similar binding affinities for most long-chain fatty acids; however, ALBP/aP2 exhibits a two to three-fold increased affinity for myristic, palmitic, oleic and linoleic acids, the predominant fatty acids of adipocytes. As measured by guanidinium hydrochloride denaturation, the stability of ALBP/aP2 is nearly 3 kcal/mol greater than that of KLBP. While the pI of ALBP/ aP2 was determined to be 9.0, that of KLBP is 6.5 suggesting differing net charges at physiological pH. Analysis of surface electrostatic properties of ALBP/aP2 and KLBP revealed similar charge polarity, although differences in the detailed charge distribution exist between the proteins. The distribution of hydrophobic patches was also different between the proteins, ALBP/ aP2 has only scattered hydrophobic surfaces while KLBP has a large hydrophobic patch near the ligand portal into the binding cavity. In sum, these results point out that despite the striking similarity between ALBP/aP2 and KLBP in tertiary structure, significant differences in ligand binding and surface properties exist between the two proteins. Hence, while it is tempting to speculate that ALBP/aP2 and KLBP are metabolically interchangeable, careful analysis suggests that the two proteins are quite distinct and likely to play unique metabolic roles. (Mol Cell Biochem 192: 33–40, 1999)

Key words

fatty acids adipocytes binding proteins electrostatics 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Banaszak LJ, Winter N, Xu Z, Bernlohr DA, Cowan S, Jones TA: Lipid-binding proteins: a family of fatty acid and retinoid transport proteins. Adv Prot Chem 45: 89–151, 1994CrossRefGoogle Scholar
  2. 2.
    Bernlohr DA, Simpson MA, Hertzel AV, Banaszak LJ: Intracellular lipid-binding proteins and their genes. Annu Rev Nutr 17: 277–303, 1997PubMedCrossRefGoogle Scholar
  3. 3.
    Veerkamp JH, Maatman RGHJ: Cytoplasmic fatty acid-binding proteins: Their structure and genes. Prog Lipid Res 34: 17–52, 1995PubMedCrossRefGoogle Scholar
  4. 4.
    Ribarik Coe N, Simpson MA, Johnston Smith A, Bernlohr DA: Targeted disruption of the adipocyte lipid binding protein impairs fat cell lipolysis and increases cellular fatty acid levels. J Biol Chem, submittedGoogle Scholar
  5. 5.
    Krieg P, Feil S, Furstenberger G, Bowden GT: Tumor-specific overexpression of a novel keratinocte lipid-binding protein: Identification and characterization of a cloned sequence activated during multistage carcinogenesis in mouse skin. J Biol Chem 238: 17362–17369, 1993Google Scholar
  6. 6.
    Kane CD, Ribarik Coe N, Vanlandingham B, Krieg P, Bernlohr DA: Expression, purification, and ligand-binding analysis of recombinant keratinocyte lipid-binding protein (MAL-1), an intracellular lipid-binding protein found overexpressed in neoplastic skin cells. Biochemistry 35: 2894–2900, 1996PubMedCrossRefGoogle Scholar
  7. 7.
    Hotamisligil GS, Johnson RS, Distel RJ, Ellis R, Papaioannou VE, Spiegelman BM: Uncoupling of obesity from insulin resistance through a targeted mutation in aP2, the adipocyte fatty acid binding protein. Science 274: 1377–1379, 1996PubMedCrossRefGoogle Scholar
  8. 8.
    Wootan MG, Bernlohr DA, Storch J: Mechanism of fluorescent fatty acid transfer from adipocyte fatty acid binding protein to membranes. Biochemistry 32: 8622–8627, 1993PubMedCrossRefGoogle Scholar
  9. 9.
    Wootan MG, Storch J: Regulation of fluorescent fatty acid transfer from adipocyte and heart fatty acid binding proteins by acceptor membrane lipid composition and structure. J Biol Chem 269: 10517–10523, 1994PubMedGoogle Scholar
  10. 10.
    Herr FM, Matarese V, Bernlohr DA, Storch J: Surface lysine residues modulate the collisional transfer of fatty acid from adipocyte fatty acid binding protein to membranes. Biochemistry 34: 11840–11845, 1995PubMedCrossRefGoogle Scholar
  11. 11.
    Herr FM, Aronson J, Storch J: Role of portal region lysine residues in electrostatic interactions between heart fatty acid binding protein and phospholipid membranes. Biochemistry 35: 1296–1303, 1996PubMedCrossRefGoogle Scholar
  12. 12.
    Xu Z, Buelt MK, Banaszak U, Bernlohr DA: Expression, purification, and crystallization of the adipocyte lipid binding protein. J Biol Chem 266: 14367–14370, 1991PubMedGoogle Scholar
  13. 13.
    Kane CD, Bernlohr DA: A simple assay for intracellular lipid-binding proteins using displacement of 1-anilinonaphthalene-8-sulfonic acid. Anal Biochem 233: 197–204, 1996PubMedCrossRefGoogle Scholar
  14. 14.
    Buelt MK, Xu Z, Banaszak W, Bernlohr DA: Structural and functional characterization of the phosphorylated adipocyte lipid-binding protein (pp 15). Biochemistry 31: 3493–3499, 1992PubMedCrossRefGoogle Scholar
  15. 15.
    Pace CN: Thestabilityofglobularproteins. Crit Rev Biochem 3: 1–43, 1975CrossRefGoogle Scholar
  16. 16.
    Peitsch MC: Protein modeling by E-mail. Bio/Technology 13: 658–660, 1995CrossRefGoogle Scholar
  17. 17.
    Peitsch MC: ProMod and Swiss-Model: Internet-based tools for automated comparative protein modelling. Biochem Soc Trans 24: 274–279, 1996PubMedGoogle Scholar
  18. 18.
    Nicholls A, Sharp KA, Honig B: Protein folding and association: Insights from the interfacial and thermodynamic properties of hydrocarbons. Proteins 11: 281–296, 1991PubMedCrossRefGoogle Scholar
  19. 19.
    Sayle RA, Milner-White EJ: RASMOL: Biomolecular graphics for all. TIBS 20: 374, 1995PubMedGoogle Scholar
  20. 20.
    Bernlohr DA, Doering TL, Kelly U Jr, Lane MD: Tissue specific expression of p422 protein, a putative lipid carrier, in mouse adipocytes. Biochem Biophys Res Comm 132: 850–855, 1985PubMedCrossRefGoogle Scholar
  21. 21.
    Richieri GV, Ogata RT, Kleinfeld AM: 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. J Biol Chem 269: 23918–23930, 1994PubMedGoogle Scholar
  22. 22.
    Vorum H, Brodersen R, Kragh-Hansen U, Pedersen AO: Solubility of long-chain fatty acids in phosphate buffer at pH 7.4. Biochim Biophys Acta 1126: 135–142, 1992PubMedCrossRefGoogle Scholar
  23. 23.
    Prows DR, Murphy EJ, Schroeder F: Intestinal and liver fatty acid binding proteins differentially affect fatty acid uptake and esterification in L-cells. Lipids 30: 907–910, 1995PubMedCrossRefGoogle Scholar
  24. 24.
    Murphy EJ, Prows DR, Jefferson JR, Schroeder F: Liver fatty acid-binding protein expression in transfected fibroblasts stimulates fatty acid uptake and metabolism. Biochim Biophys Acta-Lipids and Lipid Metab 1301: 191–198, 1996CrossRefGoogle Scholar
  25. 25.
    Hsu K-T, Storch J: Fatty acid transfer from liver and intestinal fatty acid-binding proteins to membranes occurs by different mechanisms. J Biol Chem 271: 13317–13323, 1996PubMedCrossRefGoogle Scholar
  26. 26.
    Xu Z, Bernlohr DA, Banamak U: Crystal structure of recombinant murine adipocyte lipid-binding protein. Biochemistry 31: 3484–3492, 1992PubMedCrossRefGoogle Scholar
  27. 27.
    Bernlohr DA, Angus CW, Lane MD, Bolanowski MA, Kelly U Jr: Expression of specific mRNAs during adipose differentiation: Identification of an mRNA encoding a homologue of myelin P2 protein. Proc Natl Acad Sci USA 81: 5468–5472, 1984PubMedCrossRefGoogle Scholar
  28. 28.
    LiCata VJ, Bernlohr DA: Surface properties of adipocyte lipid binding protein. Response to lipid binding and comparison with homologous proteins. Proteins (in press)Google Scholar

Copyright information

© Springer Science+Business Media Dordrecht 1999

Authors and Affiliations

  • Melanie A. Simpson
    • 1
  • Vince J. LiCata
    • 1
  • Natalie Ribarik Coe
    • 1
  • David A. Bernlohr
    • 1
  1. 1.Department of BiochemistryUniversity of MinnesotaSt. PaulUSA

Personalised recommendations