The adipocyte fatty acid-binding protein binds to membranes by electrostatic interactions

Elizabeth R. Smith, Judith Storch

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

The adipocyte fatty acid-binding protein (AFABP) is believed to transfer unesterified fatty acids (FA) to phospholipid membranes via a collisional mechanism that involves ionic interactions between lysine residues on the protein surface and phospholipid headgroups. This hypothesis is derived largely from kinetic analysis of FA transfer from AFABP to membranes. In this study, we examined directly the binding of AFABP to large unilamellar vesicles (LUV) of differing phospholipid compositions. AFABP bound LUV containing either cardiolipin or phosphatidic acid, and the amount of protein bound depended upon the mol % anionic phospholipid. The K(a) for CL or PA in LUV containing 25 mol % of these anionic phospholipids was approximately 2 x 103 M-1. No detectable binding occurred when AFABP was mixed with zwitterionic membranes, nor when acetylated AFABP in which surface lysines had been chemically neutralized was mixed with anionic membranes. The binding of AFABP to acidic membranes depended upon the ionic strength of the incubation buffer: ≥200 mM NaCl reduced protein-lipid complex formation in parallel with a decrease in the rate of FA transfer from AFABP to negatively charged membranes. It was further found that AFABP, but not acetylated AFABP, prevented cytochrome c, a well characterized peripheral membrane protein, from binding to membranes. These results directly demonstrate that AFABP binds to anionic phospholipid membranes and suggest that, although generally described as a cytosolic protein, AFABP may behave as a peripheral membrane protein to help target fatty acids to and/or from intracellular sites of utilization.

Original languageEnglish
Pages (from-to)35325-35330
Number of pages6
JournalJournal of Biological Chemistry
Volume274
Issue number50
DOIs
StatePublished - Dec 10 1999
Externally publishedYes

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Fatty Acid-Binding Proteins
Coulomb interactions
Static Electricity
Adipocytes
Membranes
Phospholipids
Unilamellar Liposomes
Fatty Acids
Membrane Proteins
Lysine
Phosphatidic Acids
Proteins
Cardiolipins
Cytochromes c
Ionic strength
Protein Binding
Osmolar Concentration
Buffers

ASJC Scopus subject areas

  • Biochemistry

Cite this

The adipocyte fatty acid-binding protein binds to membranes by electrostatic interactions. / Smith, Elizabeth R.; Storch, Judith.

In: Journal of Biological Chemistry, Vol. 274, No. 50, 10.12.1999, p. 35325-35330.

Research output: Contribution to journalArticle

Smith, Elizabeth R. ; Storch, Judith. / The adipocyte fatty acid-binding protein binds to membranes by electrostatic interactions. In: Journal of Biological Chemistry. 1999 ; Vol. 274, No. 50. pp. 35325-35330.
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