Dynamics
A paper published by the Nevins group at Duke University in 2008 demonstrated that the a bistable hysteric E2F switch underlies the restriction point. E2F promotes its own activation, and also promotes the inhibition of its own inhibitor (pRb), forming two feedback loops (among others) that are important in establishing bistable systems. The authors of this study used a destabilized GFP-system under the control of the E2F promoter as a readout of E2F activity. Serum-starved cells were stimulated with varying serum concentrations, and the GFP readout was recorded at a single-cell level. They found that the GFP reporter was either on or off, indicating that E2F was either completely activated or deactivated at all of the different serum levels analyzed. Further experiments, in which they analyzed the history-dependence of the E2F system confirmed that it operates as a hysteretic bistable switch.
Read more about this topic: Restriction Point
Famous quotes containing the word dynamics:
“Anytime we react to behavior in our children that we dislike in ourselves, we need to proceed with extreme caution. The dynamics of everyday family life also have a way of repeating themselves.”
—Cathy Rindner Tempelsman (20th century)