| Description: | Crystallins are separated into two classes:taxon-specific, or enzyme, and ubiquitous. The latter classconstitutes the major proteins of vertebrate eye lens and maintainsthe transparency and refractive index of the lens. Since lenscentral fiber cells lose their nuclei during development, thesecrystallins are made and then retained throughout life, making themextremely stable proteins. Mammalian lens crystallins are dividedinto alpha, beta, and gamma families; beta and gamma crystallinsare also considered as a superfamily. Alpha and beta families arefurther divided into acidic and basic groups. Seven protein regionsexist in crystallins: four homologous motifs, a connecting peptide,and N- and C-terminal extensions. Beta-crystallins, the mostheterogeneous, 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 toself-associate to form dimers or to form heterodimers with otherbeta-crystallins. This gene, a beta basic group member, is part ofa gene cluster with beta-A4, beta-B1, and beta-B2. [provided byRefSeq]. |
