Tear lipocalin: structure, function and molecular mechanisms of action.
نویسندگان
چکیده
Human tear lipocalin (TL), or von Ebner's gland protein, accounts for about 15-33% of the protein in tears. I-4 TL has been identified in lacrimal gland, von Ebner' s gland, prostate, nasal and tracheal mucosa and skin.512 TL was recognized as a member of the lipocalin family when its primary sequence was determined.7.I3 .14 Lipocalins form a functionally diverse group of proteins with extremely varied amino acid sequences. yet some similar structural properties (Fig. 1). Eight strands (A-H) are arranged in aß-barrel and are joined by loops between the ß-strands. 15-19 Many of the lipocalins, including TL, are believed to function as dimers. 20. 21 There are highly conserved regions that are important to ligand affinity and lipocalin stability. Most lipocalins have 1-3 disulfides bonds and one in particular is conserved and may play a role in modulating ligand binding. 15. 22 A completely conserved tryptophan on the Astrand is implicated in ligand binding and prevention of oxidation of retinol, as weIl as protein stability of various lipocalins.23.24 A variety of general functions for TL have been suggested based on its binding of lipid molecules. These include the binding and transport of phospholipids, fatty acids, cholesterol, retinol, tocopherol, and tastants, the scavenging of harmful lipids such as phthalates and lipid products of inflammation, antimicrobial activity, or capture of fatty acids that inhibit antimicrobial activity, endonuclease activity, and cysteine proteinase inhibition.6.7.25-33
منابع مشابه
Mass spectrometric identification of phospholipids in human tears and tear lipocalin.
PURPOSE The purpose of this article was to identify by mass spectrometry phosphocholine lipids in stimulated human tears and determine the molecules bound to tear lipocalin or other proteins. METHODS Tear proteins were separated isocratically from pooled stimulated human tears by gel filtration fast performance liquid chromatography. Separation of tear lipocalin was confirmed by SDS tricine g...
متن کاملInteraction of tear lipocalin with lysozyme and lactoferrin.
The interaction of human tear lipocalin with lysozyme and lactoferrin was studied by electron paramagnetic resonance (EPR) spectroscopy. TL mutants I98C and F99C were spin labeled with MTSL and its derivative. The spectra demonstrated that at sites C98 and C99 the mobility of the nitroxides was reduced in the presence of lysozyme, lactoferrin, but not albumin. The reduced mobility was manifeste...
متن کاملDecreased tear lipocalin concentration in patients with meibomian gland dysfunction.
BACKGROUND/AIM Recent studies have demonstrated that tear lipocalin (TL) and phospholipids have a crucial role in maintaining tear film stability. The level of TL in patients with meibomian gland dysfunction (MGD) was examined and these data were correlated with the severity of their clinical disorder. METHODS 12 patients with obstructive MGD, 12 patients with seborrhoeic MGD, and 12 age matc...
متن کاملSCIENTIFIC REPORT Decreased tear lipocalin concentration in patients with meibomian gland dysfunction
Background/aim: Recent studies have demonstrated that tear lipocalin (TL) and phospholipids have a crucial role in maintaining tear film stability. The level of TL in patients with meibomian gland dysfunction (MGD) was examined and these data were correlated with the severity of their clinical disorder. Methods: 12 patients with obstructive MGD, 12 patients with seborrhoeic MGD, and 12 age matc...
متن کاملTear lipocalin captures exogenous lipid from abnormal corneal surfaces.
Purpose. The cornea is protected by apical hydrophilic transmembrane mucins and tears. In pathologic states the mucin barrier is disrupted, creating potential for meibomian lipids to adhere more strongly. Undisplaced lipids create an unwettable surface. The hypothesis that pathologic ocular surfaces alter lipid binding and the ability of tear proteins to remove lipids was tested. Methods. Corne...
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عنوان ژورنال:
- Advances in experimental medicine and biology
دوره 506 Pt A شماره
صفحات -
تاریخ انتشار 2002