AB-crystallin

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The role of the IF, and particularly the keratin filament system, in resisting the forces of mechanical stress has been well established. However, IFs also play a role in countering metabolic stress. Perhaps the best example is the cytoprotective role played by the simple epithelial keratins, K8/18. However, vimentin, desmin, peripherin, GFAP, the lens proteins phakinin, and filensin and other keratins have also been shown to associate with members of the small heat shock protein (HSP) family, including HSP27 and aB-crystallin (reviewed in Coulombe and Wong, 2004 Marceau et al., 2001 Nicholl and Quinlan, 1994). 

Subjecting cells to various forms of stress has been shown to dramatically reorganize IF networks, concomitant with the redistribution of normally soluble aB-crystallins to these networks, resulting in resistance to... 

We have validated this approach in a study of 33 sequential biopsies from four patients, where 2-D analysis detected 13 proteins that were upregulated more than 5-fold in association with acute rejection in all four patients. Subsequently, two of these proteins (aB-crystallin, tropomyosin) were measured by ELISA and found to be present at significantly higher levels in serum samples associated with biopsy-proven acute rejection (Borozdenkova et al., 2004). 

P-amyloid precursor protein aB-crystallin Capulet Chd64 CGI 0724 Ebl... 

Fig. 2. H- N HSQC spectrum of l5N-labelled aB-crystallin (of total molecular mass -650 kDa, I him in 50 mM phosphate buffer, pH 7.2). Data were acquired at 25°C on a Varian INOVA-500 NMR spectrometer. Cross-peaks are observed for the highly mobile C-terminal extension encompassing the last 12 amino acids of the protein.

H.E. Hoover D.J. Thuerauf, J.J Martindale and C.C. Glcmbotski, aB-crystallin gene induction and phosphorylation by MKK6-activated p38. A potential role for aB-crystallin as a target of the p38 branch of the cardiac stress response, J. Biol. Chem. 275, 23825-23833 (2000). 

P. Eaton, W. Fuller, J.R. Bell and M.J. Shattock, aB crystallin translocation and phosphorylation signal transduction pathways and preconditioning in the isolated rat heart, J. Mol. Cell. Cardiol. 33,1659-1671 (2001). 

The oligomeric structures listed in Table I are all derived from purified recombinant proteins, typically expressed in E. coli. However, in many organisms multiple sHsps are found in the same cellular compartment and coassembly of sHsps into heterooligomers is often observed. A primary case in point is the a-crystallins a A- and aB-crystallin are complexed together in the eye lens at an a A B ratio of 3 1, forming polydisperse aggregates with an average molecular mass of 800 kDa... 

Proteolytic processing of extracellular matrix components occurs in the cornea and the trabecular meshwork which contain a number of matrix metalloproteinases (MMP), these enzymes have also been found in virtually all areas of the eye (Sivak and Fini, 2002). The lens is the tissue that has been the most studied using 2D gels, about 2000 spots are observed, mostly a, P, y ciystallins and their modified forms (Jungblut et al, 1998). Post-translational modifications like oxydation or glycation of the ciystallins lead to protein aggregation and eventually to lens opacification, that is cataract (Steely and Clark, 2000). The expression pattern of crystallin is modified in several models of cataract and an atypical form of aB crystallin has been found in the lens of some patients (Jimenez-Asensio et al, 1999 Fig. 4). 

There are two closely related a-crystallins in the domestic fowl, aA and aB. Both are encoded in closely related genes, each having three exons and two introns, but aA-crystallin is only expressed in the lens, whereas aB is expressed in a number of tissues. The sequence of duck aB-crystallin is very similar to both the small heat shock protein (hsp-27) and large... 

Lee, D.C., Kim, R.Y. Wistow, G.J. (1993). An avian aB-crystallin non-lens expression and sequence similarities with both small (hsp27) and large (hsp70) heat shock proteins.. Mol Biol, 232, 1221-6. 

Scotting, P., McDermott H. Meyer, R.J. (1991). Ubiquitin— protein conjugates and aB crystallin are selectively present in cells undergoing major cytomorphological reorganisation in early chicken embryos. FEBS Lett., 285, 75—9. 

Endoplasmic reticulum stress, decreased activity of SIRT1, oxidative stress, and putative roie of aB-crystallin... 

Muth IE, Barthel K, Bahr M et al. (2009) Proinflam -matory cell stress in sporadic inclusion body myositis muscle overexpression of aB-crystallin is associated with amyloid precursor protein and accumulation of p-amyloid. J Neurol Neurosurg Psychiatry 80, 1344-1349. 

E.P. Roquemore, M.R. Chevrier, R.J. Cotter and G.W. Hart, Biochemistry, 1996, 35, 3578-3586, Dynamic 0-GlcNAcylation of the small heat shock protein aB-crystallin. 

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