CRYGS explained

Gamma-crystallin S is a protein that in humans is encoded by the CRYGS gene.^[1]

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. Gamma-crystallins are a homogeneous group of highly symmetrical, monomeric proteins typically lacking connecting peptides and terminal extensions. They are differentially regulated after early development. This gene encodes a protein initially considered to be a beta-crystallin but the encoded protein is monomeric and has greater sequence similarity to other gamma-crystallins. This gene encodes the most significant gamma-crystallin in adult eye lens tissue.

Whether due to aging or mutations in specific genes, gamma-crystallins have been involved in cataract formation.

Further reading

• Graw J . The crystallins: genes, proteins and diseases . Biol. Chem. . 378 . 11 . 1331–48 . 1998 . 9426193 . 10.1515/bchm.1997.378.11.1299.
• Slingsby C, Clout NJ . Structure of the crystallins . Eye . 13 (Pt 3b) . 3. 395–402 . 2000 . 10627816 . 10.1038/eye.1999.113. free .
• Zarina S, Abbasi A, Zaidi ZH . Primary structure of beta s-crystallin from human lens . Biochem. J. . 287 . Pt 2. 375–81 . 1992 . 1445197 . 10.1042/bj2870375. 1133175 .
• Brakenhoff RH . Human gamma-crystallin genes. A gene family on its way to extinction . J. Mol. Biol. . 216 . 3 . 519–32 . 1991 . 2258929 . 10.1016/0022-2836(90)90380-5 . vanc. Aarts HJ . Reek FH . 3 . Lubsen . NH . Schoenmakers . JG .
• Meakin SO, Du RP, Tsui LC, Breitman ML . Gamma-crystallins of the human eye lens: expression analysis of five members of the gene family . Mol. Cell. Biol. . 7 . 8 . 2671–9 . 1987 . 3670288 . 10.1128/mcb.7.8.2671. 367883 .
• Smith JB . The complete sequence of human lens gamma s-crystallin . Biochem. J. . 307 . Pt 2. 407–10 . 1995 . 7733876 . 10.1042/bj3070407. 1136663 . vanc. Yang Z . Lin P . 3 . Zaidi . Z . Abbasi . A . Russell . P .
• Zarina S . Three-dimensional model and quaternary structure of the human eye lens protein gamma S-crystallin based on beta- and gamma-crystallin X-ray coordinates and ultracentrifugation . Protein Sci. . 3 . 10 . 1840–6 . 1995 . 7849599 . 10.1002/pro.5560031023 . 2142617 . vanc. Slingsby C . Jaenicke R . 3 . Srinivasan . N. . Slingsby . C. . Jaenicke . R. .
• Lampi KJ . 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 . 1997 . 8999933 . 10.1074/jbc.272.4.2268 . vanc. Ma Z . Shih M . 3 . Shearer . TR . Smith . JB . Smith . DL . David . LL . free .
• Wistow G, Sardarian L, Gan W, Wyatt MK . The human gene for gammaS-crystallin: alternative transcripts and expressed sequences from the first intron . Mol. Vis. . 6 . 79–84 . 2000 . 10837510 .
• Purkiss AG . The X-ray crystal structure of human gamma S-crystallin C-terminal domain . J. Biol. Chem. . 277 . 6 . 4199–205 . 2002 . 11706012 . 10.1074/jbc.M110083200 . vanc. Bateman OA . Goodfellow JM . 3 . Lubsen . NH . Slingsby . C . free .
• MacCoss MJ . Shotgun identification of protein modifications from protein complexes and lens tissue . Proc. Natl. Acad. Sci. U.S.A. . 99 . 12 . 7900–5 . 2002 . 12060738 . 10.1073/pnas.122231399 . 122992 . vanc. McDonald WH . Saraf A . 3 . Sadygov . R . Clark . JM . Tasto . JJ . Gould . KL . Wolters . D . Washburn . M . 2002PNAS...99.7900M . free .
• Lapko VN, Purkiss AG, Smith DL, Smith JB . Deamidation in human gamma S-crystallin from cataractous lenses is influenced by surface exposure . Biochemistry . 41 . 27 . 8638–48 . 2002 . 12093281 . 10.1021/bi015924t .
• Lapko VN, Smith DL, Smith JB . S-methylated cysteines in human lens gamma S-crystallins . Biochemistry . 41 . 50 . 14645–51 . 2003 . 12475213 . 10.1021/bi0267700 .
• Strausberg RL . Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences . Proc. Natl. Acad. Sci. U.S.A. . 99 . 26 . 16899–903 . 2003 . 12477932 . 10.1073/pnas.242603899 . 139241 . vanc. Feingold EA . Grouse LH . 3 . Derge . JG . Klausner . RD . Collins . FS . Wagner . L . Shenmen . CM . Schuler . GD . 2002PNAS...9916899M . free .
• Annunziata O, Ogun O, Benedek GB . Observation of liquid–liquid phase separation for eye lens γS-crystallin . Proc. Natl. Acad. Sci. U.S.A. . 100 . 3 . 970–4 . 2003 . 12529503 . 10.1073/pnas.242746499 . 298710 . 2003PNAS..100..970A . free .
• Craghill J, Cronshaw AD, Harding JJ . The identification of a reaction site of glutathione mixed-disulphide formation on gammaS-crystallin in human lens . Biochem. J. . 379 . Pt 3 . 595–600 . 2004 . 14763903 . 10.1042/BJ20031367 . 1224128 .
• Gerhard DS . The Status, Quality, and Expansion of the NIH Full-Length cDNA Project: The Mammalian Gene Collection (MGC) . Genome Res. . 14 . 10B . 2121–7 . 2004 . 15489334 . 10.1101/gr.2596504 . 528928 . vanc. Wagner L . Feingold EA . 3 . Shenmen . CM . Grouse . LH . Schuler . G . Klein . SL . Old . S . Rasooly . R .
• Sun H . Gamma-S crystallin gene (CRYGS) mutation causes dominant progressive cortical cataract in humans . J. Med. Genet. . 42 . 9 . 706–10 . 2006 . 16141006 . 10.1136/jmg.2004.028274 . 1736139 . vanc. Ma Z . Li Y . 3 . Liu . B . Li . Z . Ding . X . Gao . Y . Ma . W . Tang . X .

Notes and References

1. Web site: Entrez Gene: CRYGS crystallin, gamma S.