Tandemly arrayed genes (TAGs) are a gene cluster created by tandem duplications,[1] a process in which one gene is duplicated and the copy is found adjacent to the original.[2] They serve to encode large numbers of genes at a time.
TAGs represent a large proportion of genes in a genome, including between 14% and 17% of the human, mouse, and rat genomes.[2] TAG clusters may have as few as two genes, with small clusters predominating, but may consist of hundreds of genes.[2] An example are tandem clusters of rRNA encoding genes. These genes are transcribed faster than they would be if only a single copy of the gene was available. Additionally, a single RNA gene may not be able to provide enough RNA, but tandem repeats of the gene allow sufficient RNA to be produced. For example, cells in a human embryo contain between five and ten million ribosomes, and cell number doubles within 24 hours. In order to provide the necessary ribosomes, multiple RNA polymerases must consecutively transcribe multiple rRNA genes.[3]
In some species, such as Arabidopsis thaliana and Oryza sativa, most TAGs are the result of unequal chromosomal crossover during genetic recombination.[4]
See also
editNotes
edit- ^ Pan & Zhang 2008.
- ^ a b c Lajoie, Bertrand & El-Mabrouk 2007, p. 96.
- ^ Lodish, Harvey; Arnold Berk; Chris Kaiser; Monty Krieger; Anthony Bretscher; Hidde Ploegh; Angelika Amon; Matthew Scott (2013). "Genes, Genomics, and Chromosomes". In Beth McHenry (ed.). Molecular Cell Biology (7 ed.). New York: W.H. Freeman Company. pp. 227–230. ISBN 9781429234139.
- ^ Barker, Baute & Liu 2012, p. 157.
References
edit- Barker, Michael S.; Baute, Gregory J.; Liu, Shao-Lun (5 March 2012). "Duplications and Turnover in Plant Genomes". In Wendel, Jonathan F.; Greilhuber, Johann; Dolezel, Jaroslav; et al. (eds.). Plant Genome Diversity Volume 1: Plant Genomes, their Residents, and their Evolutionary Dynamics. Plant Genome Diversity. Vol. 1. Springer Science & Business Media. pp. 155–169. doi:10.1007/978-3-7091-1130-7_11. ISBN 9783709111307.
- Pan, Deng; Zhang, Liqing (2008). "Tandemly arrayed genes in vertebrate genomes". International Journal of Genomics. 2008. Hindawi Publishing Corporation: 545269. doi:10.1155/2008/545269. PMC 2547482. PMID 18815629.
- Lajoie, Mathieu; Bertrand, Denis; El-Mabrouk, Nadia (16–18 September 2007). "Evolution of tandemly-arrayed genes in multiple species". In Tesler, Glenn; Durand, Dannie (eds.). Comparative Genomics: RECOMB 2007, International Workshop, RECOMB-CG 2007, San Diego, CA, USA, September 16–18, 2007, Proceedings. RECOMB 2007, International Workshop, RECOMB-CG 2007. Lecture Notes in Bioinformatics. Vol. 4751. San Diego: Springer Science & Business Media. pp. 96–107. ISBN 9783540749592. ISSN 0302-9743.
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