The mechanism of gap creation by a multifunctional nuclease during base excision repair.

During base excision repair, a transient single-stranded DNA (ssDNA) gap is produced at the apurinic/apyrimidinic (AP) site. Exonuclease III, capable of performing both AP endonuclease and exonuclease activity, are responsible for gap creation in bacteria. We used single-molecule fluorescence resonance energy transfer to examine the mechanism of gap creation.

A ginsenoside-Rh1, a component of ginseng saponin, activates estrogen receptor in human breast carcinoma MCF-7 cells.

We have examined the possibility that a component of Panax ginseng, ginsenoside-Rh1, acts by binding to steroid hormone receptors such as receptors for estrogen, glucocorticoid, androgen, and retinoic acid. Ginsenoside-Rh1 activated the transcription of the estrogen-responsive luciferase reporter gene in MCF-7 breast cancer cells at a concentration of 50 microM. Activation was inhibited by the specific estrogen receptor antagonist ICI 182,780, indicating that the estrogenic effect of ginsenoside-Rh1 is estrogen receptor dependent.