Background information
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. Gamma-crystallins are ahomogeneous group of highly symmetrical, monomeric proteinstypically lacking connecting peptides and terminal extensions. Theyare differentially regulated after early development. This geneencodes a protein initially considered to be a beta-crystallin butthe encoded protein is monomeric and has greater sequencesimilarity to other gamma-crystallins. This gene encodes the mostsignificant gamma-crystallin in adult eye lens tissue. Whether dueto aging or mutations in specific genes, gamma-crystallins havebeen involved in cataract formation. [provided by RefSeq, Jul2008].
