Crystallins are separated into two classes: taxon-specific, or enzyme, and ubiquitous. The latter class constitutes the major proteins of vertebrate eye lens and maintains the transparency and refractive index of the lens. Since lens central fiber cells lose their nuclei during development, these crystallins are made and then retained throughout life, making them extremely stable proteins. 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. This gene, a beta acidic group member, encodes two proteins (crystallin, beta A3 and crystallin, beta A1) from a single mRNA, the latter protein is 17 aa shorter than crystallin, beta A3 and is generated by use of an alternate translation initiation site. Deletion of exons 3 and 4 causes the autosomal dominant disease 'zonular cataract with sutural opacities'.
^Hogg D, Tsui LC, Gorin M, Breitman ML (Oct 1986). "Characterization of the human beta-crystallin gene Hu beta A3/A1 reveals ancestral relationships among the beta gamma-crystallin superfamily". J Biol Chem261 (26): 12420–7. PMID3745196.
^Sparkes RS, Mohandas T, Heinzmann C, Gorin MB, Zollman S, Horwitz J (Nov 1986). "Assignment of a human beta-crystallin gene to 17cen-q23". Hum Genet74 (2): 133–6. doi:10.1007/BF00282076. PMID3770741.
Hulsebos TJ, Bijlsma EK, Geurts van Kessel AH, et al. (1991). "Direct assignment of the human beta B2 and beta B3 crystallin genes to 22q11.2----q12: markers for neurofibromatosis 2.". Cytogenet. Cell Genet.56 (3-4): 171–5. doi:10.1159/000133080. PMID2055112.
Basti S, Hejtmancik JF, Padma T, et al. (1996). "Autosomal dominant zonular cataract with sutural opacities in a four-generation family.". Am. J. Ophthalmol.121 (2): 162–8. PMID8623885.
Werten PJ, Carver JA, Jaenicke R, de Jong WW (1997). "The elusive role of the N-terminal extension of beta A3- and beta A1-crystallin.". Protein Eng.9 (11): 1021–8. doi:10.1093/protein/9.11.1021. PMID8961355.
Lampi KJ, Ma Z, Shih M, et al. (1997). "Sequence analysis of betaA3, betaB3, and betaA4 crystallins completes the identification of the major proteins in young human lens.". J. Biol. Chem.272 (4): 2268–75. doi:10.1074/jbc.272.4.2268. PMID8999933.
Kannabiran C, Rogan PK, Olmos L, et al. (1998). "Autosomal dominant zonular cataract with sutural opacities is associated with a splice mutation in the betaA3/A1-crystallin gene.". Mol. Vis.4: 21. PMID9788845.
Srivastava OP, Srivastava K (1999). "Characterization of a sodium deoxycholate-activatable proteinase activity associated with betaA3/A1-crystallin of human lenses.". Biochim. Biophys. Acta1434 (2): 331–46. PMID10525151.
Graw J, Jung M, Löster J, et al. (2000). "Mutation in the betaA3/A1-crystallin encoding gene Cryba1 causes a dominant cataract in the mouse.". Genomics62 (1): 67–73. doi:10.1006/geno.1999.5974. PMID10585769.
Qi Y, Jia H, Huang S, et al. (2004). "A deletion mutation in the betaA1/A3 crystallin gene ( CRYBA1/A3) is associated with autosomal dominant congenital nuclear cataract in a Chinese family.". Hum. Genet.114 (2): 192–7. doi:10.1007/s00439-003-1049-7. PMID14598164.
Reddy MA, Bateman OA, Chakarova C, et al. (2004). "Characterization of the G91del CRYBA1/3-crystallin protein: a cause of human inherited cataract.". Hum. Mol. Genet.13 (9): 945–53. doi:10.1093/hmg/ddh110. PMID15016766.