Human tear lipocalin (TL) is an unusual member of the lipocalin protein family, since it is known to bind a large variety of lipophilic ligands in vivo and acts as a cysteine proteinase inhibitor in vitro. It is suggested to function as a physiological protection factor by scavenging lipophilic potentially harmful compounds. Since protein-protein interaction or macromolecular complexation is a common feature of many lipocalins, we applied phage display technology to identify TL interacting proteins. By panning of a human prostate cDNA phagemid library against purified TL we isolated a thioredoxin (Trx) encoding phage clone. Biochemical analysis revealed that TL indeed interacts with Trx and is reduced by this redox protein. Reduction of the TL-specific disulfide bond is of functional relevance, since the reduced protein shows a nine-fold increase in ligand affinity when tested with retinoic acid as ligand. Copyright (C) 1999 Federation of European Biochemical Societies.
Redl, B., Merschak, P., Abt, B., & Wojnar, P. (1999). Phage display reveals a novel interaction of human tear lipocalin and thioredoxin which is relevant for ligand binding. FEBS Letters, 460(1), 182–186. https://doi.org/10.1016/S0014-5793(99)01331-9