Twenty years have elapsed since cytoplasmic proteins exhibiting high-affinity binding of long-chain fatty acids were first identified (Ockner et al., Science 177:56-58, 1972). These cellular fatty acid-binding proteins (FABPs) are now well established to comprise a ligand-defined group of macromolecules belonging to a family of cytoplasmic lipid binding proteins. Unique features of the FABPs are the existence of distinct types of FABP and that these are found in a variety of tissues in remarkable abundance, with some cells expressing more than one type. The physiological significance of the FABPs has only partly been elucidated. By increasing the cytoplasmic solubilization of fatty acids, the cellular FABPs are considered to function primarily in intracellular fatty acid transport, but may also be assigned important regulatory roles in cellular lipid homeostasis as well as in the modulation of cell growth and differentiation. The broad interests in cellular FABPs has led to the organization of the 1st International Workshop on Fatty Acid-Binding Protein, held in Maastricht, the Netherlands, in 1989. Prompted by the success of the first meeting, the 2nd International Workshop on Fatty-Acid-Binding Proteins, which was held again in Maastricht, on August 31 and September 1, 1992, brought together scientific scpecialists in the field of FABP research for two days of intensive and fruitful discussion. This volume is a collection of selected papers from this conference, and thus provides the state-of-the-art knowledge of cellular FABPs. The contributors to this issue represent pioneering as well as new investigators, and also reflect the multidisciplinary nature of research in this exciting and rapidly progressing field.

Twenty years have elapsed since cytoplasmic proteins exhibiting high-affinity binding of long-chain fatty acids were first identified (Ockner et al., Science 177:56-58, 1972). These cellular fatty acid-binding proteins (FABPs) are now well established to comprise a ligand-defined group of macromolecules belonging to a family of cytoplasmic lipid binding proteins. Unique features of the FABPs are the existence of distinct types of FABP and that these are found in a variety of tissues in remarkable abundance, with some cells expressing more than one type. The physiological significance of the FABPs has only partly been elucidated. By increasing the cytoplasmic solubilization of fatty acids, the cellular FABPs are considered to function primarily in intracellular fatty acid transport, but may also be assigned important regulatory roles in cellular lipid homeostasis as well as in the modulation of cell growth and differentiation. The broad interests in cellular FABPs has led to the organization of the 1st International Workshop on Fatty Acid-Binding Protein, held in Maastricht, the Netherlands, in 1989. Prompted by the success of the first meeting, the 2nd International Workshop on Fatty-Acid-Binding Proteins, which was held again in Maastricht, on August 31 and September 1, 1992, brought together scientific scpecialists in the field of FABP research for two days of intensive and fruitful discussion. This volume is a collection of selected papers from this conference, and thus provides the state-of-the-art knowledge of cellular FABPs. The contributors to this issue represent pioneering as well as new investigators, and also reflect the multidisciplinary nature of research in this exciting and rapidly progressing field.

The cellular functions of lipid-transport proteins cannot can be obtained, as well as structural information re- garding the local environment of the spectroscopic be fully realized without a comprehensive knowledge of probe. However, changes in protein fluorescence upon their binding properties. In particular, it is important to identify physiologically important ligands and establish ligand binding are sometimes too small to quantitate. their binding affinities, stoichiometries and specificities. This is particularly true for L-FABP, which has no tryp- Since many lipid-binding proteins exhibit no enzymatic tophan residues. Also, some lipids lack intrinsic fluores- cence or paramagnetic properties, including many lipids activity, binding parameters provide an important quan- titative measure for comparing the 'activity' of various of physiological interest. In such cases, lipid analogues wild-type and mutant forms. For this purpose, binding containing structure-perturbing anthroylxoxy or doxyl assays that are quantitative, accurate and robust are de- probes are required. Lipids that do have intrinsic fluor- sirable. escence, such as parinaric acid, are labile and prone to For the intracellular fatty acid- and lipid-binding pro- oxidation. The binding of native ligands can be moni- teins, a variety of biochemical and biophysical binding tored by isotope-directed NMR techniques, provided assays have been used. The biochemical assays include that enrichment with 13C or another suitable isotope is those based on gel-filtration [1-3], equilibrium dialysis feasible. Although such NMR methods are useful for de- [4], Lipidex [5,6] and liposomes [7].