Gamma-crystallin Ais aproteinthat in humans is encoded by theCRYGAgene.[5]
Crystallinsare separated into two classes: taxon-specific, or enzyme, and ubiquitous. The latter class constitutes the major proteins of vertebrateeye lensand maintains the transparency andrefractive indexof the lens. Since lens central fiber cells lose theirnucleiduring 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 connectingpeptidesand terminal extensions. They are differentially regulated after early development. Four gamma-crystallin genes (gamma-A through gamma-D) and threepseudogenes(gamma-E, gamma-F, gamma-G) are tandemly organized in a genomic segment as agene cluster.Whether due to aging ormutationsin specific genes, gamma-crystallins have been involved incataractformation.[5]
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den Dunnen JT, Jongbloed RJ, Geurts van Kessel AH, Schoenmakers JG (1985). "Human lens gamma-crystallin sequences are located in the p12-qter region of chromosome 2".Hum. Genet.70(3): 217–21.doi:10.1007/bf00273445.PMID2991114.S2CID23745896.
Shiloh Y, Donlon T, Bruns G, et al. (1986). "Assignment of the human gamma-crystallin gene cluster (CRYG) to the long arm of chromosome 2, region q33-36".Hum. Genet.73(1): 17–9.doi:10.1007/BF00292656.PMID3011643.S2CID27997711.
Salim A, Zaidi ZH (2003). "Homology models of human gamma-crystallins: structural study of the extensive charge network in gamma-crystallins".Biochem. Biophys. Res. Commun.300(3): 624–30.doi:10.1016/S0006-291X(02)02895-4.PMID12507494.