Abstract
αB-Crystallin (CryAB) is a major stress protein in cardiac myocytes. Under pathological stress such as ischemia, it acts as a molecular chaperone to suppress protein aggregation at the Z-line and at the I-band region of myofibril and at the intercalated disk. We report here that CryAB-like immunoreactivity also exists as a relatively weak but distinct signal at the M-line in isolated Syrian hamster ventricular myocytes, using a new laser confocal immunofluorescence microscope with high resolution. Our electron microscopic examination revealed that mitochondria in the isolated myocytes carried evidence of mild ischemia. Immunoblot analysis using a polyclonal antibody against CryAB detected a single protein with molecular mass of 21kDa in Syrian hamster left ventricle. The novel localization of CryAB-like immunoreactivity in the cardiac myofibril and its possible relation to ischemia may shed light on a yet to be unraveled chaperonic function of this stress protein in the heart.
