The crystallins are water-soluble structural proteins that occur in high concentration in the cytoplasm of eye lens fibre cells. Four major groups of crystallin have been distinguished on the basis of size, charge and immunological properties: alpha-, beta- and gamma-crystallins occur in all vertebrate classes (though gamma-crystallins are low or absent in avian lenses); and delta-crystallin … expand

The crystallins are water-soluble structural proteins that occur in high concentration in the cytoplasm of eye lens fibre cells. Four major groups of crystallin have been distinguished on the basis of size, charge and immunological properties: alpha-, beta- and gamma-crystallins occur in all vertebrate classes (though gamma-crystallins are low or absent in avian lenses); and delta-crystallin is found exclusively in reptiles and birds [ PUBMED:2688200 PUBMED:7634077 ].

This entry represents beta and gamma-crystallin which form a family of related proteins [ PUBMED:2107329 PUBMED:3064189 ]. Structurally, beta- and gamma-crystallins are composed of two similar domains which, in turn, are each composed of two similar motifs with the two domains connected by a short connecting peptide. Each motif, which is about forty amino acid residues long, is folded in a distinctive 'Greek key' pattern.