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pBR322 is a plasmid and was one of the first widely used ''E. coli'' cloning vectors. Created in 1977 in the laboratory of Herbert Boyer at the University of California, San Francisco, it was named after the postdoctoral researchers who constructed it. The p stands for "plasmid," and BR for "Bolivar" and "Rodriguez." pBR322 is 4361 base pairs in length and harbors the origin of replication of plasmid pMB1, a close relative of the plasmid ColE1. pBR322 also contains the ''ampR'' gene, encoding the ampicillin resistance protein (source plasmid RSF2124) and the ''tetR'' gene, encoding the tetracycline resistance protein (source plasmid pSC101), and the ''rop'' gene, encoding a restrictor of plasmid copy number. The plasmid has unique restriction sites for more than forty restriction enzymes. 11 of these 40 sites lie within the ''tetR'' gene. There are 2 sites for restriction enzymes HindIII and ClaI within the promoter of the ''tetR'' gene. There are 6 key restriction sites inside the ''ampR'' gene. The circular sequence is numbered such that 0 is the middle of the unique EcoRI site and the count increases through the tet gene. The ampicillin resistance gene is penicillin beta-lactamase. Promoters P1 and P3 are for the beta-lactamase gene. P3 is the natural promoter, and P1 is artificially created by the ligation of two different DNA fragments to create pBR322. P2 is in the same region as P1, but it is on the opposite strand and initiates transcription in the direction of the tetracycline resistance gene. See also List of restriction enzyme cutting sites The sequence in pBR322 is〔 ==External links== *http://www.thermoscientificbio.com/uploadedFiles/Resources/pBR322-map.pdf pBR322 Map *http://www.thermoscientificbio.com/molecular-cloning/pbr322-dna/ pBR322 DNA 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「PBR322」の詳細全文を読む スポンサード リンク
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