CAG promoter

from Wikipedia, the free encyclopedia

The CAG promoter is a synthetically produced DNA fragment that is used in molecular biology , biochemistry and biotechnology as a tool in the production of recombinant proteins . The DNA construct is used to achieve a high level of gene expression in eukaryotic cells and thus to overexpress recombinant proteins. The CAG promoter was designed in Yamamura Ken-ichi's laboratory. It consists of ( C ), the human cytomegalovirus (HCMV) early enhancer element , ( A ), the promoter , the first untranslated exon and the 5 ' part of the first intron of the beta-actin gene from chickens, ( G ), the 3 ' part of the second intron and the 5' part of the third exon of the rabbit beta globin gene.

The CMV enhancer is part of many eukaryotic expression plasmids. The actin gene intron also has enhancer activity. In addition, introns in eukaryotic vectors increase gene expression. The section from the beta globin gene contains a branch point sequence which is important for splicing and a splice acceptor sequence (3'-splice site) . Even if the synthetic element is referred to as a CAG promoter, it is in the strict sense a 5 'activating element, since in addition to the promoter it also contains the CMV enhancer, intron and exon sequences.

An often used vector , pCAGGS , which contains the CAG Promoor, was constructed on the basis of a pUC vector. It also contains the polyadenylation signal of the beta globin gene.

The use of the CAG promoter also allows high expression in transgenic animals and in almost all cell types in mammals. In a transgenic mouse line, GFP could be detected in all tissues with the exception of erythrocytes and hair. When used in embryonic stem cells , the CAG promoter has the advantage that its expression is not switched off (gene silencing) .

Web links

literature

  1. ↑ Miyazaki Jun-ichi, Takaki Satoshi, Araki Kimi, Tashiro Fumi, Tominaga Akira, Takatsu Kiyoshi, Yamamura Ken-ichi: Expression vector system based on the chicken β-actin promoter directs efficient production of interleukin-5. In: Genes. 79, 1989, pp. 269-277, doi : 10.1016 / 0378-1119 (89) 90209-6 .
  2. ^ AR Buchman, P. Berg: Comparison of intron-dependent and intron-independent gene expression. In: Molecular and cellular biology. Volume 8, Number 10, October 1988, pp. 4395-4405, PMID 3185553 , PMC 365513 (free full text).
  3. ↑ H. Niwa, K. Yamamura, J. Miyazaki: Efficient selection for high-expression transfectants with a novel eukaryotic vector. In: Genes. Volume 108, Number 2, December 1991, pp. 193-199, PMID 1660837 .
  4. ↑ M. Okabe, M. Ikawa, K. Kominami, T. Nakanishi, Y. Nishimune: 'Green mice' as a source of ubiquitous green cells. In: FEBS letters. Volume 407, Number 3, May 1997, pp. 313-319, PMID 9175875 .
  5. ↑ AN Alexopoulou, JR Couchman, JR Whiteford: The CMV early enhancer / chicken beta actin (CAG) promoter can be used to drive transgene expression during the differentiation of murine embryonic stem cells into vascular progenitors. In: BMC cell biology. Volume 9, January 2008, p. 2, doi : 10.1186 / 1471-2121-9-2 , PMID 18190688 , PMC 2254385 (free full text).