Refinement of 3D structure of bovine lens αA-crystallin

Farnsworth, Patricia N.; Frauwirth, H; Groth-Vasselli, Barbara; Singh, Kamalendra

doi:10.1016/s0141-8130(98)00015-4

Cited by 24 publications

(22 citation statements)

References 53 publications

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“…The major substrates of aA and aB in the lens fibre cell are k-and bcrystallin [21], although interactions with 'house-keeping' enzymes such as enolase [70], cytoskeletal elements [71] and membrane-associated proteins also occur [72,73]. It appears that the quaternary structure of the protein with a hydrophilic exterior and a hydrophobic interior, is vital to chaperone activity, as it has been observed that the structure is conserved [74] and resistant to changes in the amino acid sequence [61]. Furthermore, the addition of a negative charge to the protein surface such as through citraconylation has been seen to increase activity [75].…”

Section: The Crystallinsmentioning

confidence: 99%

Regulation of αA- and αB-crystallins via phosphorylation in cellular homeostasis

Thornell

Aquilina

2015

Cell. Mol. Life Sci.

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αA-Crystallin (αA) and αB-crystallin (αB) are small heat shock proteins responsible for the maintenance of transparency in the lens. In non-lenticular tissues, αB is involved in both maintenance of the cytoskeleton and suppression of neurodegeneration amongst other roles. Despite their importance in maintaining cellular health, modifications and mutations to αA and αB appear to play a role in disease states such as cataract and myopathies. The list of modifications that have been reported is extensive and include oxidation, disulphide bond formation, C- and N-terminal truncation, acetylation, carboxymethylation, carboxyethylation, carbamylation, deamidation, phosphorylation and methylation. Such modifications, notably phosphorylation, are alleged to cause changes to chaperone activity by inducing substructural changes and altering subunit exchange dynamics. Although the effect modification has on the activities of αA and αB is contentious, it has been proposed that these changes are responsible for the induction of hyperactivity and are thereby indirectly responsible for protein deposition characteristic of many diseases associated with αA and αB. This review compiles all reported sites of αA and αB modifications, and investigates the role phosphorylation, in particular, plays in cellular processes.

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Section: The Crystallinsmentioning

confidence: 99%

Regulation of αA- and αB-crystallins via phosphorylation in cellular homeostasis

Thornell

Aquilina

2015

Cell. Mol. Life Sci.

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“…Numerous and in part controversial structural models have been proposed on the basis of known physicochemical properties of ␣-crystallins. Several competing three-layer models with variable numbers of subunits, a micelle-like structure, a "pitted-flexiball," a "bean with tentacles," and a GroEL-type complex are among the hypothetical models (42,78,101,295,336).…”

Section: Structure Of ␣-Heat Shock Proteinsmentioning

confidence: 99%

α-Crystallin-Type Heat Shock Proteins: Socializing Minichaperones in the Context of a Multichaperone Network

Narberhaus

2002

Microbiol Mol Biol Rev

496

415

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SUMMARY α-Crystallins were originally recognized as proteins contributing to the transparency of the mammalian eye lens. Subsequently, they have been found in many, but not all, members of the Archaea, Bacteria, and Eucarya. Most members of the diverse α-crystallin family have four common structural and functional features: (i) a small monomeric molecular mass between 12 and 43 kDa; (ii) the formation of large oligomeric complexes; (iii) the presence of a moderately conserved central region, the so-called α-crystallin domain; and (iv) molecular chaperone activity. Since α-crystallins are induced by a temperature upshift in many organisms, they are often referred to as small heat shock proteins (sHsps) or, more accurately, α-Hsps. α-Crystallins are integrated into a highly flexible and synergistic multichaperone network evolved to secure protein quality control in the cell. Their chaperone activity is limited to the binding of unfolding intermediates in order to protect them from irreversible aggregation. Productive release and refolding of captured proteins into the native state requires close cooperation with other cellular chaperones. In addition, α-Hsps seem to play an important role in membrane stabilization. The review compiles information on the abundance, sequence conservation, regulation, structure, and function of α-Hsps with an emphasis on the microbial members of this chaperone family.

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“…A role for the N terminus in providing essential stabilizing forces to smHSP oligomers has been suggested before (61,62). Recombinant ␣A-crystallin in which the complete N-terminal domain was deleted formed dimers or tetramers upon renaturation (60,63).…”

Section: Hsp27mentioning

confidence: 99%

HSP27 Multimerization Mediated by Phosphorylation-sensitive Intermolecular Interactions at the Amino Terminus

Lambert

Charette²,

Bernier

et al. 1999

Journal of Biological Chemistry

300

307

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. Using the yeast two-hybrid system, two domains were identified that were responsible for HSP27 intermolecular interactions. One domain was insensitive to phosphorylation and corresponded to the C-terminal ␣-crystallin domain. The other domain was sensitive to serine 90 phosphorylation and was located in the N-terminal region of the protein. Fusion of this N-terminal domain to firefly luciferase conferred luciferase with the capacity to form multimers that dissociated into monomers upon phosphorylation. A deletion within this domain of residues Arg 5 -Tyr 23 , which contains a WDPF motif found in most proteins of the small heat shock protein family, yielded a protein that forms only phosphorylation-insensitive dimers. We propose that HSP27 forms stable dimers through the ␣-crystallin domain. These dimers further multimerize through intermolecular interactions mediated by the phosphorylation-sensitive N-terminal domain.

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Refinement of 3D structure of bovine lens αA-crystallin

Cited by 24 publications

References 53 publications

Regulation of αA- and αB-crystallins via phosphorylation in cellular homeostasis

Regulation of αA- and αB-crystallins via phosphorylation in cellular homeostasis

α-Crystallin-Type Heat Shock Proteins: Socializing Minichaperones in the Context of a Multichaperone Network

HSP27 Multimerization Mediated by Phosphorylation-sensitive Intermolecular Interactions at the Amino Terminus

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