Ultrasensitivity in (supra)molecularly organized and crowded environments.
The ultrasensitive response of biological systems is a more sensitive one than that expected from the classical hyperbola of Michaelis-Menten kinetics, and whose physiological relevance depends upon the range of variation of substrate or effector for which ultrasensitivity is observed. Triggering and modulation of the ultrasensitive response in enzymatic and cellular systems are reviewed. Several demonstrations of ultrasensitive behavior in cellular systems and its impact on the amplification properties in signalling cascades and metabolic pathways are also highlighted. It is shown that ubiquitous cytoskeletal proteins may up- or downmodulate ultrasensitivity under physico-chemical conditions resembling those predominant in cells.
Aon
M A
MA
Instituto Tecnológico de Chascomús (IIB/INTECH, CONICET), Buenos Aires, Argentina. maon@bme.jhu.edu
Gomez-Casati
D F
DF
Iglesias
A A
AA
Cortassa
S
S
D000818:Animals; D004798:Enzymes / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D008868:Microtubule Proteins / Q000502:physiology*; D008962:Models, Theoretical; D015398:Signal Transduction / Q000502:physiology*; D013379:Substrate Specificity / Q000502:physiology
D004798:Enzymes; D046911:Macromolecular Substances; D008868:Microtubule Proteins