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Tandem repeats occur in DNA when a pattern of one or more nucleotides is repeated and the repetitions are directly adjacent to each other. Several protein domains also form tandem repeats within their amino acid primary structure, such as Armadillo repeats. However, in proteins, perfect tandem repeats are unlikely in most ''in vivo'' proteins, and most known repeats are in proteins which have been designed. An example would be: : ATTCG ATTCG ATTCG in which the sequence ATTCG is repeated three times. ==Terminology== When between 10 and 60 nucleotides are repeated, it is called a minisatellite. Those with fewer are known as microsatellites or short tandem repeats. When exactly two nucleotides are repeated, it is called a ''dinucleotide repeat'' (for example: ACACACAC…). The microsatellite instability in hereditary nonpolyposis colon cancer most commonly affects such regions. When three nucleotides are repeated, it is called a ''trinucleotide repeat'' (for example: CAGCAGCAGCAG…), and abnormalities in such regions can give rise to trinucleotide repeat disorders. When the repeat unit copy number is variable in the population being considered, it is called a variable number tandem repeat (VNTR). MeSH classifies variable number tandem repeats under minisatellites. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tandem repeat」の詳細全文を読む スポンサード リンク
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