Ischemia-induced association of the stress protein alpha B-crystallin with I-band portion of cardiac titin

N. GOLENHOFEN, A. ARBEITER, R, KOOB AND D. DRENCKHAHN. Ischemia-induced Association of the Stress Protein alphaB-crystallin with I-band Portion of Cardiac Titin. Journal of Molecular and Cellular Cardiology (2002) 34, 309-319. During ischemia the cardiac stress protein, alphaB-crystallin, was shown by immunoelectron microscopy to translocate to the N-2-line area of myofibrillar I-bands of rat cardiomyocytes where alphaB-crystallin resisted extraction with 1 M NaSCN and 2 M urea. as did titin. Actin became completely extracted under these conditions, indicating association of alphaB-crystallin with titin the only remaining non-actin cytosketetal component of I-bands outside Z-disks. Titin, extracted from ischemic pig myocardium, was shown to copurify with alphaB-crystallin. Further evidence for binding of alphaB-crystallin to titin was obtained by dot-blot assays in which biotinylated alphaB-crystallin was demonstrated to bind to the titin-enriched fraction immobilized on nitrocellulose, Binding of alphaB-crystallin to titin during cardiac ischemia could serve to stabilize titin against denaturation and might provide an endogenous mechanism to delay ischemic damage of this important elastic component of myofibrils. (C) 2002 Elsevier Science Ltd. All rights reserved.