Four features of signal transducing systems Part ll Structure and Catalysis (a)Specificity (c)Desensitization/Adaptation Signal molecule fits Receptor activation triggers binding site on its feedback circuit that shuts complementary receptor; off the receptor or removes Receptor other signals do not fit Receptor it from the cell surface Effect b)Amplification (d) Integration When enzymes activate When two signals have Signal 1 Signal 2 enzymes, the number of opposite effects on a affected molecules metabolic characteristic increases geometrically Enzyme 1 such as the concentration an enzyme cascade. of a second messenger x, Receptor or the membrane potential Vm, the regulatory outcome results from the integrated Enzyme input from both receptors.↑x] or Tv.↓ X)or V Ne△X]orVm RFour features of signal￾transducing systems