Useful Information
Human lens crystallin Beta-crystallin A4
PDB Code 3LWK Target Class Miscellaneous Target CRYBA4 Alias CRYBA4 Disease Area/Function metabolism Date Deposited Feb 24 2010 Authors
About this structure
In vertebrate lens, 30-35% of the entire mass corresponds to proteins, composed of the α-, β-, and γ-crystallins. These lens crystallins represent a diverse repertoire of structural proteins that are extremely stable and highly soluble, and contribute to the transparency and refractory power of the eye lens. Mutations of most crystalline genes hence have been associated with cataracts, a world-wide leading cause of blindness. The β- and γ-crystallins represent different subgroups of a large, ancient superfamily of evolutionarily related proteins as a result of extensive gene duplications, whilst α-crystallins (e.g. CRYAA, CRYAB) belong to the family of small heat-shock proteins some of which still retain the role as molecular chaperones.The βγ-crystallin superfamily comprises the oligomeric β classes as well as the monomeric γ classes. β-crystallins can be further classified into three basic (CRYBB1-3) and four acidic (CRYBA1-4) members believed to derive from a common ancestor. Structurally βγ-crystallins are characterized by four Greek key motifs, which are antiparallel β-sheets intercalating to form a highly-symmetrical β-sandwich domain. The four Greek key motifs of β-crystallins are each encoded individually by separate exons, whereas in the case of γ-crystallins two motifs are encoded by one single exon. Here we have determined the crystal structure of the human CRYBA4 crystallin. Recently, mutations in the CRYBA4 gene have been linked to cataract formation (Phe94Ser) and microphthalmia (Leu69Pro), a deformation resulting in small eyes.
