title: Phage display reveals a novel interaction of human tear lipocalin and thioredoxin which is relevant for ligand binding.
abstract: 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.
authors.affiliation: Institut für Mikrobiologie (Medizinische Fakultät), Universität Innsbruck, Austria. bernhard.redl@uibk.ac.at
authors.forename: B
authors.initials: B
authors.lastname: Redl
authors.forename: P
authors.initials: P
authors.lastname: Merschak
authors.forename: B
authors.initials: B
authors.lastname: Abt
authors.forename: P
authors.initials: P
authors.lastname: Wojnar
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000302:isolation & purification; D004220:Disulfides / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000737:chemistry; D005453:Fluorescence; D015723:Gene Library; D006801:Humans; D008024:Ligands; D054835:Lipocalin 1; D008297:Male; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D011485:Protein Binding; D013879:Thioredoxins / Q000737:chemistry* / Q000235:genetics; D014212:Tretinoin / Q000737:chemistry
chemical_list: D002352:Carrier Proteins; D018076:DNA, Complementary; D004220:Disulfides; D005136:Eye Proteins; C518443:LCN1 protein, human; D008024:Ligands; D054835:Lipocalin 1; C042434:tear proteins; D013879:Thioredoxins; D014212:Tretinoin