T-REx四环素诱导系统
A Tetracycline-Regulated Expression System without Viral Transactivators
The T-REx System yields higher levels of induced expression than any other regulated mammalian expression system. It utilizes the complete CMV promoter and adds control elements from the bacterial tetracycline resistance operon to effectively repress and derepress transcription from one of the strongest mammalian promoter sequences known (1,2).

Specific Activation
The T-REx System uses a repressor mechanism that blocks transcription from the powerful CMV promoter in the absence of tetracycline. Because the T-REx System elements do not use viral transactivators, you can achieve high-level expression from the complete CMV promoter without secondary, non-specific activation of host genes.

The T-REx Mechanism
The T-REx transcriptional control elements are illustrated in Figure 1. Two tetracycline operator sequences (TetO2) have been inserted between the TATA box of the CMV promoter and the transcriptional start site. The TetO2 sequence itself has no effect on expression. When the tetracycline repressor protein (TR) is present, it effectively binds the TetO2 sites and blocks transcription initiation. Tetracycline added to the culture medium binds to, and changes the conformation of, the TR protein. This change causes the TR protein to release the TetO2 sites, derepressing transcription from the CMV promoter. The result is high-level expression of the gene of interest (Figure 2). Expression levels can be modulated based on the tetracycline concentration and can be induced to levels that are achieved with constitutive CMV expression vectors.
T-REx is a powerful inducible mammalian expression system that allows you to regulate expression from the complete human cytomegalovirus (CMV) enhancer-promoter. T-RExinducible expression vectors offer the following features:

 Complete CMV enhancer-promoter sequence containing two copies of the tetracycline operator TetO2 sequence for high-level regulated expression
 Zeocin or hygromycin resistance gene for effective selection of stable mammalian cell lines
 Large multiple cloning site to simplify cloning

In addition, pcDNA4/TO/myc-His offers a c-myc epitope for rapid detection of the recombinant protein with an Anti-myc Antibody and a polyhistidine (6xHis) sequence for simple purification of the recombinant protein with nickel-chelating resin and detection with Anti- His(C-term) Antibody.

The regulatory vector, pcDNA6/TR, is provided for high-level expression of the tetracycline repressor (TR) protein. This vector expresses the Blasticidin resistance gene for rapid selection of mammalian cell lines that stably express the TR protein.

LOCUS       pcDNA4/TO/Myc-His A	5151 bp 	DNA	SYN
DEFINITION  pcDNA4/TO/Myc-His A
ACCESSION   
KEYWORDS    
SOURCE      
  ORGANISM  other sequences; artificial sequences; vectors.
FEATURES             Location/Qualifiers
     source          1..5151
                     /organism="pcDNA4/TO/Myc-His A"
                     /mol_type="other DNA"
     promoter        236..812
                     /label="CMV_immearly_promoter"
     misc_feature    315..602
                     /label="CAG_enhancer"
     misc_feature    769..789
                     /label="CMV_fwd_primer"
     promoter        770..893
                     /label="CMV_promoter"
     promoter        782..955
                     /label="CMV2_promoter"
     misc_feature    820..859
                     /label="tetO"
     misc_feature    869..893
                     /label="LNCX_primer"
     misc_feature    complement(1158..1175)
                     /label="BGH_rev_primer"
     terminator      1161..1388
                     /label="bGH_PA_terminator"
     rep_origin      1451..1757
                     /label="f1_origin"
     misc_feature    complement(1871..1891)
                     /label="pBABE_3_primer"
     misc_feature    complement(1877..2093)
                     /label="SV40_enhancer"
     promoter        1889..2158
                     /label="SV40_promoter"
     rep_origin      2057..2134
                     /label="SV40_origin"
     misc_feature    2119..2138
                     /label="SV40pro_F_primer"
     promoter        2252..2319
                     /label="EM7_promoter"
     gene            2320..2691
                     /label="bleo"
                     /gene="bleo"
     misc_feature    2320..2694
                     /label="sh_ble"
     terminator      2827..2946
                     /label="SV40_PA_terminator"
     misc_feature    2915..2934
                     /label="EBV_rev_primer"
     promoter        complement(2990..3008)
                     /label="M13_reverse_primer"
     misc_feature    complement(3007..3029)
                     /label="M13_pUC_rev_primer"
     promoter        complement(3043..3072)
                     /label="lac_promoter"
     rep_origin      complement(3381..4000)
                     /label="pBR322_origin"
     gene            complement(4155..5015)
                     /label="Ampicillin"
                     /gene="Ampicillin"
     CDS             complement(4155..5015)
                     /label="ORF frame 2"
                     /translation="MSIQHFRVALIPFFAAFCLPVFAHPETLVKVKDAEDQLGARVGY
                     IELDLNSGKILESFRPEERFPMMSTFKVLLCGAVLSRIDAGQEQLGRRIHYSQNDLVE
                     YSPVTEKHLTDGMTVRELCSAAITMSDNTAANLLLTTIGGPKELTAFLHNMGDHVTRL
                     DRWEPELNEAIPNDERDTTMPVAMATTLRKLLTGELLTLASRQQLIDWMEADKVAGPL
                     LRSALPAGWFIADKSGAGERGSRGIIAALGPDGKPSRIVVIYTTGSQATMDERNRQIA
                     EIGASLIKHW*"
     promoter        complement(5057..5085)
                     /label="AmpR_promoter"
                     /translation="MSIQHFRVALIPFFAAFCLPVFAHPETLVKVKDAEDQLGARVGY
                     IELDLNSGKILESFRPEERFPMMSTFKVLLCGAVLSRIDAGQEQLGRRIHYSQNDLVE
                     YSPVTEKHLTDGMTVRELCSAAITMSDNTAANLLLTTIGGPKELTAFLHNMGDHVTRL
                     DRWEPELNEAIPNDERDTTMPVAMATTLRKLLTGELLTLASRQQLIDWMEADKVAGPL
                     LRSALPAGWFIADKSGAGERGSRGIIAALGPDGKPSRIVVIYTTGSQATMDERNRQIA
                     EIGASLIKHW*"
ORIGIN
    1 GACGGATCGG GAGATCTCCC GATCCCCTAT GGTCGACTCT CAGTACAATC TGCTCTGATG
   61 CCGCATAGTT AAGCCAGTAT CTGCTCCCTG CTTGTGTGTT GGAGGTCGCT GAGTAGTGCG
  121 CGAGCAAAAT TTAAGCTACA ACAAGGCAAG GCTTGACCGA CAATTGCATG AAGAATCTGC
  181 TTAGGGTTAG GCGTTTTGCG CTGCTTCGCG ATGTACGGGC CAGATATACG CGTTGACATT
  241 GATTATTGAC TAGTTATTAA TAGTAATCAA TTACGGGGTC ATTAGTTCAT AGCCCATATA
  301 TGGAGTTCCG CGTTACATAA CTTACGGTAA ATGGCCCGCC TGGCTGACCG CCCAACGACC
  361 CCCGCCCATT GACGTCAATA ATGACGTATG TTCCCATAGT AACGCCAATA GGGACTTTCC
  421 ATTGACGTCA ATGGGTGGAG TATTTACGGT AAACTGCCCA CTTGGCAGTA CATCAAGTGT
  481 ATCATATGCC AAGTACGCCC CCTATTGACG TCAATGACGG TAAATGGCCC GCCTGGCATT
  541 ATGCCCAGTA CATGACCTTA TGGGACTTTC CTACTTGGCA GTACATCTAC GTATTAGTCA
  601 TCGCTATTAC CATGGTGATG CGGTTTTGGC AGTACATCAA TGGGCGTGGA TAGCGGTTTG
  661 ACTCACGGGG ATTTCCAAGT CTCCACCCCA TTGACGTCAA TGGGAGTTTG TTTTGGAACC
  721 AAAATCAACG GGACTTTCCA AAATGTCGTA ACAACTCCGC CCCATTGACG CAAATGGGCG
  781 GTAGGCGTGT ACGGTGGGAG GTCTATATAA GCAGAGCTCT CCCTATCAGT GATAGAGATC
  841 TCCCTATCAG TGATAGAGAT CGTCGACGAG CTCGTTTAGT GAACCGTCAG ATCGCCTGGA
  901 GACGCCATCC ACGCTGTTTT GACCTCCATA GAAGACACCG GGACCGATCC AGCCTCCGGA
  961 CTCTAGCGTT TAAACTTAAG CTTGGTACCG AGCTCGGATC CACTAGTCCA GTGTGGTGGA
 1021 ATTCTGCAGA TATCCAGCAC AGTGGCGGCC GCTCGAGTCT AGAGGGCCCT TCGAACAAAA
 1081 ACTCATCTCA GAAGAGGATC TGAATATGCA TACCGGTCAT CATCACCATC ACCATTGAGT
 1141 TTAAACCCGC TGATCAGCCT CGACTGTGCC TTCTAGTTGC CAGCCATCTG TTGTTTGCCC
 1201 CTCCCCCGTG CCTTCCTTGA CCCTGGAAGG TGCCACTCCC ACTGTCCTTT CCTAATAAAA
 1261 TGAGGAAATT GCATCGCATT GTCTGAGTAG GTGTCATTCT ATTCTGGGGG GTGGGGTGGG
 1321 GCAGGACAGC AAGGGGGAGG ATTGGGAAGA CAATAGCAGG CATGCTGGGG ATGCGGTGGG
 1381 CTCTATGGCT TCTGAGGCGG AAAGAACCAG CTGGGGCTCT AGGGGGTATC CCCACGCGCC
 1441 CTGTAGCGGC GCATTAAGCG CGGCGGGTGT GGTGGTTACG CGCAGCGTGA CCGCTACACT
 1501 TGCCAGCGCC CTAGCGCCCG CTCCTTTCGC TTTCTTCCCT TCCTTTCTCG CCACGTTCGC
 1561 CGGCTTTCCC CGTCAAGCTC TAAATCGGGG CATCCCTTTA GGGTTCCGAT TTAGTGCTTT
 1621 ACGGCACCTC GACCCCAAAA AACTTGATTA GGGTGATGGT TCACGTAGTG GGCCATCGCC
 1681 CTGATAGACG GTTTTTCGCC CTTTGACGTT GGAGTCCACG TTCTTTAATA GTGGACTCTT
 1741 GTTCCAAACT GGAACAACAC TCAACCCTAT CTCGGTCTAT TCTTTTGATT TATAAGGGAT
 1801 TTTGGGGATT TCGGCCTATT GGTTAAAAAA TGAGCTGATT TAACAAAAAT TTAACGCGAA
 1861 TTAATTCTGT GGAATGTGTG TCAGTTAGGG TGTGGAAAGT CCCCAGGCTC CCCAGGCAGG
 1921 CAGAAGTATG CAAAGCATGC ATCTCAATTA GTCAGCAACC AGGTGTGGAA AGTCCCCAGG
 1981 CTCCCCAGCA GGCAGAAGTA TGCAAAGCAT GCATCTCAAT TAGTCAGCAA CCATAGTCCC
 2041 GCCCCTAACT CCGCCCATCC CGCCCCTAAC TCCGCCCAGT TCCGCCCATT CTCCGCCCCA
 2101 TGGCTGACTA ATTTTTTTTA TTTATGCAGA GGCCGAGGCC GCCTCTGCCT CTGAGCTATT
 2161 CCAGAAGTAG TGAGGAGGCT TTTTTGGAGG CCTAGGCTTT TGCAAAAAGC TCCCGGGAGC
 2221 TTGTATATCC ATTTTCGGAT CTGATCAGCA CGTGTTGACA ATTAATCATC GGCATAGTAT
 2281 ATCGGCATAG TATAATACGA CAAGGTGAGG AACTAAACCA TGGCCAAGTT GACCAGTGCC
 2341 GTTCCGGTGC TCACCGCGCG CGACGTCGCC GGAGCGGTCG AGTTCTGGAC CGACCGGCTC
 2401 GGGTTCTCCC GGGACTTCGT GGAGGACGAC TTCGCCGGTG TGGTCCGGGA CGACGTGACC
 2461 CTGTTCATCA GCGCGGTCCA GGACCAGGTG GTGCCGGACA ACACCCTGGC CTGGGTGTGG
 2521 GTGCGCGGCC TGGACGAGCT GTACGCCGAG TGGTCGGAGG TCGTGTCCAC GAACTTCCGG
 2581 GACGCCTCCG GGCCGGCCAT GACCGAGATC GGCGAGCAGC CGTGGGGGCG GGAGTTCGCC
 2641 CTGCGCGACC CGGCCGGCAA CTGCGTGCAC TTCGTGGCCG AGGAGCAGGA CTGACACGTG
 2701 CTACGAGATT TCGATTCCAC CGCCGCCTTC TATGAAAGGT TGGGCTTCGG AATCGTTTTC
 2761 CGGGACGCCG GCTGGATGAT CCTCCAGCGC GGGGATCTCA TGCTGGAGTT CTTCGCCCAC
 2821 CCCAACTTGT TTATTGCAGC TTATAATGGT TACAAATAAA GCAATAGCAT CACAAATTTC
 2881 ACAAATAAAG CATTTTTTTC ACTGCATTCT AGTTGTGGTT TGTCCAAACT CATCAATGTA
 2941 TCTTATCATG TCTGTATACC GTCGACCTCT AGCTAGAGCT TGGCGTAATC ATGGTCATAG
 3001 CTGTTTCCTG TGTGAAATTG TTATCCGCTC ACAATTCCAC ACAACATACG AGCCGGAAGC
 3061 ATAAAGTGTA AAGCCTGGGG TGCCTAATGA GTGAGCTAAC TCACATTAAT TGCGTTGCGC
 3121 TCACTGCCCG CTTTCCAGTC GGGAAACCTG TCGTGCCAGC TGCATTAATG AATCGGCCAA
 3181 CGCGCGGGGA GAGGCGGTTT GCGTATTGGG CGCTCTTCCG CTTCCTCGCT CACTGACTCG
 3241 CTGCGCTCGG TCGTTCGGCT GCGGCGAGCG GTATCAGCTC ACTCAAAGGC GGTAATACGG
 3301 TTATCCACAG AATCAGGGGA TAACGCAGGA AAGAACATGT GAGCAAAAGG CCAGCAAAAG
 3361 GCCAGGAACC GTAAAAAGGC CGCGTTGCTG GCGTTTTTCC ATAGGCTCCG CCCCCCTGAC
 3421 GAGCATCACA AAAATCGACG CTCAAGTCAG AGGTGGCGAA ACCCGACAGG ACTATAAAGA
 3481 TACCAGGCGT TTCCCCCTGG AAGCTCCCTC GTGCGCTCTC CTGTTCCGAC CCTGCCGCTT
 3541 ACCGGATACC TGTCCGCCTT TCTCCCTTCG GGAAGCGTGG CGCTTTCTCA ATGCTCACGC
 3601 TGTAGGTATC TCAGTTCGGT GTAGGTCGTT CGCTCCAAGC TGGGCTGTGT GCACGAACCC
 3661 CCCGTTCAGC CCGACCGCTG CGCCTTATCC GGTAACTATC GTCTTGAGTC CAACCCGGTA
 3721 AGACACGACT TATCGCCACT GGCAGCAGCC ACTGGTAACA GGATTAGCAG AGCGAGGTAT
 3781 GTAGGCGGTG CTACAGAGTT CTTGAAGTGG TGGCCTAACT ACGGCTACAC TAGAAGGACA
 3841 GTATTTGGTA TCTGCGCTCT GCTGAAGCCA GTTACCTTCG GAAAAAGAGT TGGTAGCTCT
 3901 TGATCCGGCA AACAAACCAC CGCTGGTAGC GGTGGTTTTT TTGTTTGCAA GCAGCAGATT
 3961 ACGCGCAGAA AAAAAGGATC TCAAGAAGAT CCTTTGATCT TTTCTACGGG GTCTGACGCT
 4021 CAGTGGAACG AAAACTCACG TTAAGGGATT TTGGTCATGA GATTATCAAA AAGGATCTTC
 4081 ACCTAGATCC TTTTAAATTA AAAATGAAGT TTTAAATCAA TCTAAAGTAT ATATGAGTAA
 4141 ACTTGGTCTG ACAGTTACCA ATGCTTAATC AGTGAGGCAC CTATCTCAGC GATCTGTCTA
 4201 TTTCGTTCAT CCATAGTTGC CTGACTCCCC GTCGTGTAGA TAACTACGAT ACGGGAGGGC
 4261 TTACCATCTG GCCCCAGTGC TGCAATGATA CCGCGAGACC CACGCTCACC GGCTCCAGAT
 4321 TTATCAGCAA TAAACCAGCC AGCCGGAAGG GCCGAGCGCA GAAGTGGTCC TGCAACTTTA
 4381 TCCGCCTCCA TCCAGTCTAT TAATTGTTGC CGGGAAGCTA GAGTAAGTAG TTCGCCAGTT
 4441 AATAGTTTGC GCAACGTTGT TGCCATTGCT ACAGGCATCG TGGTGTCACG CTCGTCGTTT
 4501 GGTATGGCTT CATTCAGCTC CGGTTCCCAA CGATCAAGGC GAGTTACATG ATCCCCCATG
 4561 TTGTGCAAAA AAGCGGTTAG CTCCTTCGGT CCTCCGATCG TTGTCAGAAG TAAGTTGGCC
 4621 GCAGTGTTAT CACTCATGGT TATGGCAGCA CTGCATAATT CTCTTACTGT CATGCCATCC
 4681 GTAAGATGCT TTTCTGTGAC TGGTGAGTAC TCAACCAAGT CATTCTGAGA ATAGTGTATG
 4741 CGGCGACCGA GTTGCTCTTG CCCGGCGTCA ATACGGGATA ATACCGCGCC ACATAGCAGA
 4801 ACTTTAAAAG TGCTCATCAT TGGAAAACGT TCTTCGGGGC GAAAACTCTC AAGGATCTTA
 4861 CCGCTGTTGA GATCCAGTTC GATGTAACCC ACTCGTGCAC CCAACTGATC TTCAGCATCT
 4921 TTTACTTTCA CCAGCGTTTC TGGGTGAGCA AAAACAGGAA GGCAAAATGC CGCAAAAAAG
 4981 GGAATAAGGG CGACACGGAA ATGTTGAATA CTCATACTCT TCCTTTTTCA ATATTATTGA
 5041 AGCATTTATC AGGGTTATTG TCTCATGAGC GGATACATAT TTGAATGTAT TTAGAAAAAT
 5101 AAACAAATAG GGGTTCCGCG CACATTTCCC CGAAAAGTGC CACCTGACGT C

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