CRYAB

From Wikipedia, the free encyclopedia

Crystallin, alpha B
Identifiers
Symbol(s)	CRYAB; CRYA2; CTPP2; HSPB5
External IDs	OMIM: 123590 MGI: 88516 HomoloGene: 68209
Gene ontology Molecular Function: • structural constituent of eye lens • unfolded protein binding Cellular Component: • soluble fraction • insoluble fraction • nucleus • cytoplasm • plasma membrane • Z disc • contractile fiber Biological Process: • protein folding • muscle contraction • transmembrane receptor protein tyrosine kinase signaling pathway • muscle development • visual perception
RNA expression pattern
More reference expression data
Orthologs
	Human	Mouse
Entrez	1410	12955
Ensembl	ENSG00000109846	ENSMUSG00000032060
Uniprot	P02511	Q52L78
Refseq	NM_001885 (mRNA) NP_001876 (protein)	NM_009964 (mRNA) NP_034094 (protein)
Location	Chr 11: 111.28 - 111.29 Mb	Chr 9: 50.5 - 50.51 Mb
Pubmed search	[1]	[2]

Crystallin, alpha B, also known as CRYAB, is a human gene.

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.^[1]

[edit] See also

• Alpha crystallin

[edit] References

[edit] Further reading