This gene is a member of the beta-crystallin family. Beta crystallins, along with alpha and gamma crystallins, are the major proteins found in the eye lens. These proteins maintain the refractive index of the lens whilst also maintaining its transparency. Since lens central fiber cells lose their nuclei during development, crystallins are made and then retained throughout life, making them extremely stable proteins. Beta and gamma crystallins are considered be a superfamily and have a similar domain architecture, including four Greek Key motifs. Beta-crystallins form aggregates of different sizes and are able to self-associate to form dimers or to form heterodimers with other beta-crystallins. The protein encoded by this gene may have Ca2+-binding activity and could be associated with potential functions in the hippocampus and in sperm. Targeted knockout of this gene in mouse induces age-related cataract. A chain-terminating mutation in a similar gene in human was found to cause type 2 cerulean cataracts. [provided by RefSeq, Feb 2015]