Response to Comment on “‘Load-Induced Modulation of Signal Transduction Networks’: Reconciling Ultrasensitivity with Bifunctionality?”

Sci. Signal., 3 January 2012
Vol. 5, Issue 205, p. lc2
DOI: 10.1126/scisignal.2002716

Response to Comment on “‘Load-Induced Modulation of Signal Transduction Networks’: Reconciling Ultrasensitivity with Bifunctionality?”

  1. Peng Jiang1,
  2. Alejandra C. Ventura2,
  3. Eduardo D. Sontag3,
  4. Sofia D. Merajver4,
  5. Alexander J. Ninfa1,*, and
  6. Domitilla Del Vecchio5,*
  1. 1Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109–0606, USA.
  2. 2Instituto de Fisiología, Biología Molecular y Neurosciencias, COINCET-UBA, and Laboratorio de Fisiología y Biología Molecular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, Buenos Aires C1428EHA, Argentina.
  3. 3Department of Mathematics, Rutgers University, New Brunswick, NJ 08854–8019, USA.
  4. 4Department of Internal Medicine, Comprehensive Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA.
  5. 5Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
  1. *Corresponding authors. E-mail, aninfa{at}umich.edu (A.J.N.); ddv{at}mit.edu (D.D.V.)

Abstract

Straube suggests that a model that reflects the bifunctional nature of the cycle enzyme uridylyltransferase/uridylyl-removing enzyme (UTase/UR) should be used, in which the UT and UR activities are distinct and reciprocally regulated activity states of the enzyme, and notes that if such a model is used, the effects of retroactivity at intermediate stimulation will be different. However, such a model does not accurately match the observed enzyme regulatory properties and fails to predict the ultrasensitive response obtained in the experiments. Here, we argue that modeling the UTase/UR enzyme as a bifunctional enzyme with reciprocally regulated activity states misses important aspects of the system.

Citation:

P. Jiang, A. C. Ventura, E. D. Sontag, S. D. Merajver, A. J. Ninfa, and D. Del Vecchio, Response to Comment on “‘Load-Induced Modulation of Signal Transduction Networks’: Reconciling Ultrasensitivity with Bifunctionality?”. Sci. Signal. 5, lc2 (2012).
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