CRYAA

Crystallin, alpha A
Identifiers
Symbols	CRYAA ; CRYA1; CTRCT9; HSPB4
External IDs	OMIM: 123580 MGI: 88515 HomoloGene: 48053 GeneCards: CRYAA Gene
Gene ontology Molecular function • structural constituent of eye lens • protein binding • identical protein binding • metal ion binding • unfolded protein binding Cellular component • nucleus • cytoplasm • extracellular exosome Biological process • visual perception • negative regulation of intracellular transport • protein refolding • negative regulation of apoptotic process • response to stimulus • protein homooligomerization Sources: Amigo / QuickGO
RNA expression pattern
File:PBB GE CRYAA 210199 at tn.png
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	1409	12954
Ensembl	ENSG00000160202	ENSMUSG00000024041
UniProt	P02489	P24622
RefSeq (mRNA)	NM_000394	NM_001278569
RefSeq (protein)	NP_000385	NP_001265498
Location (UCSC)	Chr 21: 6.56 – 6.56 Mb	Chr 17: 31.68 – 31.68 Mb
PubMed search	[1]	[2]

Alpha-crystallin A chain is a protein that in humans is encoded by the CRYAA 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. Defects in this gene cause autosomal dominant congenital cataract (ADCC).

Interactions

CRYAA has been shown to interact with CRYBB2, Hsp27, CRYGC and CRYAB.

Further reading

This article incorporates text from the United States National Library of Medicine, which is in the public domain.