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Crystallin, alpha B
Protein CRYAB PDB 2KLR.png
Rendering based on PDB 2KLR.
Available structures
PDB Ortholog search: PDBe, RCSB
External IDs OMIM123590 MGI88516 HomoloGene68209 GeneCards: CRYAB Gene
RNA expression pattern
PBB GE CRYAB 209283 at tn.png
More reference expression data
Species Human Mouse
Entrez 1410 12955
Ensembl ENSG00000109846 ENSMUSG00000032060
UniProt P02511 P23927
RefSeq (mRNA) NM_001289807 NM_001289782
RefSeq (protein) NP_001276736 NP_001276711
Location (UCSC) Chr 11:
111.78 – 111.79 Mb
Chr 9:
50.75 – 50.76 Mb
PubMed search [1] [2]

Alpha-crystallin B chain is a protein that in humans is encoded by the CRYAB gene.[1]


Crystallins are separated into two classes: taxon-specific, or enzyme, and ubiquitous. The latter class constitutes the major proteins of vertebrate eye lens and maintains the transparency and refractive index of the lens. Since lens central fiber cells lose their nuclei during development, these crystallins are made and then retained throughout life, making them extremely stable proteins. Mammalian lens crystallins are divided into alpha, beta, and gamma families; beta and gamma crystallins are also considered as a superfamily. Alpha and beta families are further divided into acidic and basic groups.

Seven protein regions exist in crystallins: four homologous motifs, a connecting peptide, and N- and C-terminal extensions. Alpha crystallins are composed of two gene products: alpha-A and alpha-B, for acidic and basic, respectively. Alpha crystallins can be induced by heat shock and are members of the small heat shock protein (sHSP also known as the HSP20) family. They act as molecular chaperones although they do not renature proteins and release them in the fashion of a true chaperone; instead they hold them in large soluble aggregates. Post-translational modifications decrease the ability to chaperone.

These heterogeneous aggregates consist of 30-40 subunits; the alpha-A and alpha-B subunits have a 3:1 ratio, respectively. Two additional functions of alpha crystallins are an autokinase activity and participation in the intracellular architecture. Alpha-A and alpha-B gene products are differentially expressed; alpha-A is preferentially restricted to the lens and alpha-B is expressed widely in many tissues and organs. Elevated expression of alpha-B crystallin occurs in many neurological diseases; a missense mutation cosegregated in a family with a desmin-related myopathy.[2]


CRYAB has been shown to interact with:

See also[edit]


  1. ^ Jeanpierre C, Austruy E, Delattre O, Jones C, Junien C (March 1993). "Subregional physical mapping of an alpha B-crystallin sequence and of a new expressed sequence D11S877E to human 11q". Mamm Genome 4 (2): 104–8. doi:10.1007/BF00290434. PMID 8431633. 
  2. ^ "Entrez Gene: CRYAB crystallin, alpha B". 
  3. ^ a b c d Fu L, Liang J (February 2002). "Detection of protein-protein interactions among lens crystallins in a mammalian two-hybrid system assay". J. Biol. Chem. 277 (6): 4255–60. doi:10.1074/jbc.M110027200. PMID 11700327. 
  4. ^ Sugiyama Y, Suzuki A, Kishikawa M, Akutsu R, Hirose T, Waye M et al. (January 2000). "Muscle develops a specific form of small heat shock protein complex composed of MKBP/HSPB2 and HSPB3 during myogenic differentiation". J. Biol. Chem. 275 (2): 1095–104. PMID 10625651. 
  5. ^ Kato K, Shinohara H, Goto S, Inaguma Y, Morishita R, Asano T (April 1992). "Copurification of small heat shock protein with alpha B crystallin from human skeletal muscle". J. Biol. Chem. 267 (11): 7718–25. PMID 1560006. 
  6. ^ Boelens W, Croes Y, de Jong W (January 2001). "Interaction between alphaB-crystallin and the human 20S proteasomal subunit C8/alpha7". Biochim. Biophys. Acta 1544 (1-2): 311–9. PMID 11341940. 

Further reading[edit]

  • Derham B, Harding J (1999). "Alpha-crystallin as a molecular chaperone". Progress in retinal and eye research 18 (4): 463–509. doi:10.1016/S1350-9462(98)00030-5. PMID 10217480. 
  • Calinisan V, Gravem D, Chen R, Brittin S, Mohandas N, Lecomte M et al. (2006). "New insights into potential functions for the protein 4.1 superfamily of proteins in kidney epithelium". Front. Biosci. 11: 1646–66. doi:10.2741/1911. PMID 16368544. 

External links[edit]