A Non-Equilibrium Steady-State Theory of Phosphorylation-Dephosphorylation Switch in Cellular Signalling

  • Date: 09/18/2007

Hong Qian (University of Washington)


University of British Columbia


We present a mathematical theory for a biochemical switch system, which
can be either the phosphorylation-dephosphorylation cycle (PdPC)
reactions catalyzed by a kinase and a phosphatase, or GTPase cycles
catalyzed by a guanine exchange factor (GEF) and a GTPase activating
protein (GAP). The theory is based on the recently developed
open-system nonequilibrium thermodynamics, the chemical master
equation, and the traditional enzyme kinetics. We show how
ultrasensitivity, as a new form of cooperativity, arisies in an open
system, and the role of cellular energy in the functioning of switches.
We also investigate PdPC/GTPase systems with feedbacks and how it leads
to various nonlinear bifurcations.

Other Information: 

MITACS Math Biology Seminar 2007