Crystallin Beta B3 (CRYbB3)

Crystallins are separated into two classes: taxon-specific, or enzyme, and ubiquitous. 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. CRYbB3, a beta basic group member, is part of a gene cluster with beta-A4, beta-B1, and beta-B2.