CRYAB gene

The CRYAB gene (CRYAB stands for: Crystallin Alpha B) is a protein coding gene localized on chromsome 11q23.1. Alternative splicing leads to several transcript variants.

The lentil crystallins of mammals are divided into alpha, beta and gamma families. Alpha-crystallins consist of two gene products: alpha-A and alpha-B, for acidic and basic respectively. Alpha-crystallins can be induced by heat shock and belong to the family of small heat shock proteins (HSP20). They act as molecular chaperones, although they do not renature and release the proteins like a true chaperone, but retain them in large soluble aggregates. These heterogeneous aggregates consist of 30-40 subunits, with the alpha-A and alpha-B subunits each having a ratio of 3:1.

The encoded protein has been termed a "moonlighting protein" due to its ability to fulfill mechanistically distinct functions. Alpha-A and alpha-B gene products are expressed differently; alpha-A is preferentially restricted to the lens, while alpha-B is expressed in many tissues and organs. Increased expression of alpha-B crystallin occurs in many neurological diseases; a missense mutation was detected in a family with desmin-related myopathy.

1. Mao YW et al. (2004) Human alphaA- and alphaB-crystallins bind to Bax and Bcl-X(S) to sequester their translocation during staurosporine-induced apoptosis. Cell Death Differ11:512-526.
2. Savarese M et al. (2020) Panorama of the distal myopathies. Acta Myol 39:245-265.