The molecular chaperone alpha-crystallin incorporated into red cell ghosts protects membrane Na/K-ATPase against glycation and oxidative stress.
Alpha-crystallin, a molecular chaperone and lens structural protein protects soluble enzymes against heat-induced aggregation and inactivation by a variety of molecules. In this study we investigated the chaperone function of alpha-crystallin in a more physiological system in which alpha-crystallin was incorporated into red cell 'ghosts'. Its ability to protect the intrinsic membrane protein Na/K-ATPase from external stresses was studied. Red cell ghosts were created by lysing the red cells and removing cytoplasmic contents by size-exclusion chromatography. The resulting ghost cells retain Na/K-ATPase activity. alpha-Crystallin was incorporated in the cells on resealing and the activity of Na/K-ATPase assessed by ouabain-sensitive 86Rb uptake. Incubation with fructose, hydrogen peroxide and methylglyoxal (compounds that have been implicated in diabetes and cataract formation) were used to test inactivation of the Na/K pump. Intracellular alpha-crystallin protected against the decrease in ouabain sensitive 86Rb uptake, and therefore against inactivation induced by all external modifiers, in a dose-dependent manner.
Derham
Barry K
BK
Nuffield Laboratory of Ophthalmology, University of Oxford, UK.
Ellory
J Clive
JC
Bron
Anthony J
AJ
Harding
John J
JJ
D000255:Adenosine Triphosphate / Q000097:blood; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000502:physiology*; D006031:Glycosylation; D006461:Hemolysis; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D018832:Molecular Chaperones / Q000097:blood; D010042:Ouabain / Q000494:pharmacology; D018384:Oxidative Stress / Q000502:physiology*; D012413:Rubidium / Q000097:blood / Q000493:pharmacokinetics; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood*; D013395:Sucrose / Q000494:pharmacology; D038201:alpha-Crystallins / Q000097:blood*
D018832:Molecular Chaperones; D038201:alpha-Crystallins; D013395:Sucrose; D010042:Ouabain; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium