English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

DT-diaphorase, a homodimeric flavoenzyme, can provide for a defence mechanism against carcinogenesis mediated by dietary or environmental quinones as well as bioactivate quinone-containing chemotherapeutic drugs. Human cell lines and strains have been identified with very low or undetectable enzymatic activity and a C to T transition at nucleotide 609 of the DT-diaphorase cDNA. This single base change is predicted to result in a proline to serine change in amino acid 187. Human cells homozygous for this base transition fail to exhibit Western blot reactivity for DT-diaphorase, suggesting that this substitution results in protein instability. To directly test whether this base change affects DT-diaphorase enzymatic activity and/or protein stability in vivo, mammalian expression vectors containing DT-diaphorase cDNA with or without the nucleotide 609 base transition were transiently transfected in COS-1 cells. Co-transfection with a human growth hormone expression vector allowed normalization for transfection efficiency. COS-1 transfectants expressing the C to T base change displayed at least a tenfold reduction in DT-diaphorase activity (P &lt; 0.001) and a two- to threefold reduction in protein levels compared with wild-type transfectants. These results are the first to detect the presence of DT-diaphorase protein coded for by the 609 base transition in mammalian cells and confirm its predicted reduced enzymatic activity.

Transfection of COS-1 cells with DT-diaphorase cDNA: role of a base change at position 609