CPC C12N 15/67 (2013.01) [C12N 15/66 (2013.01); C12N 15/85 (2013.01); C12Y 105/01003 (2013.01)] | 20 Claims |
1. An expression vector comprising the following (a), (b) and (c):
(a) a translation-impaired dihydrofolate reductase gene cassette (translation-impaired DHFR gene cassette) comprising a region with altered codons, wherein the altered codons comprise GCA for alanine, CGA for arginine, AAU for asparagine, GAU for aspartic acid, UGU for cysteine, CAA for glutamine, GAA for glutamic acid, GGU for glycine, CAU for histidine, UUA for leucine, AAA for lysine, CCA for proline, UUU for phenylalanine, UCA for serine, ACU for threonine, UAU for tyrosine, and/or GUA for valine, and wherein the region with altered codons accounts for 30% or more of the full length of the DHFR gene from the 5′ end of the DHFR gene;
(b) a gene cassette comprising a cloning site for integration of a foreign gene between a transcriptionally active promoter and a stable polyadenylation signal; and
(c) a ubiquitously acting chromatin opening element (UCOE),
wherein the UCOE comprises the nucleotide sequence as shown in SEQ ID NO: 1.
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