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amplifycascade

amplifycascade - if Pip-heir H0 Epinephrine(in bloodstream...

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Unformatted text preview: if}; Pip-heir H0 Epinephrine (in bloodstream) Liver Membranebound adenylate cyclaseA cAMP+PP (inactive) (inactive) , actiwii'i‘oe a Ntckfimkm llsccirreli (”N/lie” Epinephrine receptor site HORMONES AND SECOND MESSENGERS cell m "b ne l» WWW Mag! E to” Protein kinase —————-> Protein kinase + GAMP a W‘QP (active) App 2,. Van‘s-Mg kw»? ATP \ g " enigma; w“: Phosphorylase kinase — _ wPhosphc-phosphorylase Ca2+ Mgr kinase (active) éghwgka ADP ATP 3 FMA‘H PMflAW'fiV mu...- m .Mw~‘u.‘* -.;.« t in.» . ”73:33:59" P“°S‘€§éill$s""’ K Mimi-cal via p SP‘AWW‘ m Glycogen +P. —-—-—---—-—> o—Glucose 1—PO4 phosphogiucomutase J phosphatase WM WW WWW) l o-Glucose + pl Figure 25-1 0 Schematic of the stimulation of glyco— genolysis in the liver by epinephrine. WKWN ma—v-o, o~Giucose (in bloodstream) which, after its release into the blood, binds to specific receptor sites on the outer surface of the membrane of liver cells (a target organ). The fact that the blood concentration of released epineph- rine is only about 10’9 M exemplifies the high degree of specific recognition (selective affinity) between hormones and their recep- tor sites. The binding of epinephrine to liver cells results in the stimulation of adenylate cyclase (an enzyme bound to the inner membrane) to synthesize CAMP. The enzyme is specific for ATP and converts the nucleoside triphosphate into CAMP and PPi (Fig- ure 25—10). The hormone—induced synthesis of CAMP, the intra— cellular, or second, messenger, triggers the following cascade of cellular events, which terminates in an increased rate of glycogenolysis. seedsgfifiemxagm mww.;:.x;2qm;h;§i?j.‘e-‘Iileufilxmamfiuxibm- 6;; l ...
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