Behaviors of cycle 1 as a function of , the total protein in cycle 1.

<p>The kinase for this cycle is denoted by and the phosphatase by . The abscissa are scaled by the characteristic range , cf. Eq. (1). A) Two cases are considered for cycle 1, which is said deactivated if and activated if . B-C) Increase of the intermediate complex when cycle 1 is respectively deactivated or activated. D-E) Variations of activated and non-activated proteins in the two cases and . The graphs were obtained by solving Eqs.(16)-(18) with the following parameters : , M, M, ; panels (B-D) : M.; panels (C-E) : M.</p

Motifs of short signaling pathways illustrating the concept of retroactive signaling in (A) a 2-cycle cascade and (B) in a 3-cycle cascade.

<p>Thick arrows indicate the direction of signaling.</p

Retroactive signaling in multi-cycle pathways.

<p>M for all to , except for (A)–(C) M, and for (D) M. (A) is varied in the range [M] such that goes from to . M, M, M, MM, M. (B) same but is varied on the range and M. (C) identical to (A) except that cycle 2 is deactivated, with MM. (D) M, M, M, M, M, M, MM, MM.</p

Phosphorylated fraction of protein 2 as a function of 2 control parameters of the downstream cycle 1, namely and .

<p>The graphs are obtained by solving Eqs.(16)-(18) with the following parameters : , M, M; On the left figures (B,D,F,H) cycle 2 is assumed deactivated, with MM. These values are swapped for the right figures (C,E,G,I) where cycle 2 is assumed activated. Panels (B,C,F,G) : cycle 1 is either deactivated (M), or activated (M). On panels (D,E,H,I), phosphatase is varied from to (so that varies from 0 to 2). Panels (D,H) : for the upper curve the total protein 1 is M and for the lower curve M. Panel (E,I) : for the upper curve the total protein 1 is M and for the lower curve M.</p