3)Four features of signal-transducing systems Part II Structure and Catalysis (a)Specificity (c) Desensitization/Adaptation Signal molecule fits Receptor activation triggers binding site on its a feedback circuit that shuts off the receptor or removes Receptor complementary receptor other signals do not fit. Receptor it from the cell surface Effect Response (b)Amplification (d)Integration when enzymes activate Signal When two signals have Signal 1 Signal 2 enzymes, the number of opposite effects on a affected molecules metabolic characteristic increases geometrically such as the concentration in an enzyme cascade. Enzyme 1 of a second messenger X, Receptor(Receptor or the membrane potential results from the integrated input from both receptors.↑ X]or TV↓ X]or v Net△ X]or v name 3313 Response(3) Four features of signal-transducing systems