alpha-crystallin A chain; heat shock protein beta-4; HspB4 (CRYAA, CRYA1, HSPB4)

Function

• may contribute to the transparency & refractive index of the lens
• deamidation of Asn-101 in lens occurs mostly during the first 30 years of age
  • deamidation of Asn-101 ~5% during the next 40 years resulting in a maximum of ~50% deamidation during a lifetime
• phosphorylation on Ser-122 seems to be developmentally regulated
  • absent in the first months of life
    • appears during the first 12 years of human lifetime
    • relative amount of phosphorylated form does not change over the lifetime

Structure

• O-glycosylated; contains N-acetylglucosamine side chains
• belongs to the small heat shock protein (HSP20) family

Compartment

• cytoplasm, nucleus
• translocates to the nucleus during heat shock & resides in nuclear speckles

Pathology

• defects in CRYAA are a cause of autosomal dominant cataracts

More general terms

• protein subunit
• heat shock protein [hsp]-20 family

Component of

• alpha-crystallin

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=1409
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:1409
• OMIM: https://mirror.omim.org/entry/123580
• OMIM: https://mirror.omim.org/entry/604219
• UniProt: http://www.uniprot.org/uniprot/P02489.html