Beta-crystallin B1 is a protein that in humans is encoded by the CRYBB1gene.[5][6] Variants in CRYBB1 are associated with autosomal dominant congenital cataract. [7][8]
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.
Beta-crystallins, the most heterogeneous, differ by the presence of the C-terminal extension (present in the basic group, none in the acidic group). Beta-crystallins form aggregates of different sizes and are able to self-associate to form dimers or to form heterodimers with other beta-crystallins. This gene, a beta basic group member, undergoes extensive cleavage at its N-terminal extension during lens maturation. It is also a member of a gene cluster with beta-A4, beta-B2, and beta-B3.[6]
^"Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^"Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^Hulsebos TJ, Gilbert DJ, Delattre O, Smink LJ, Dunham I, Westerveld A, Thomas G, Jenkins NA, Copeland NG (Mar 1996). "Assignment of the beta B1 crystallin gene (CRYBB1) to human chromosome 22 and mouse chromosome 5". Genomics. 29 (3): 712–8. doi:10.1006/geno.1995.9947. PMID8575764.
