Page 86 - Teknik Menjawab Soalan PSPM Biologi
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Mechanism of Cyclic AMP Activation Non-steroid hormone (eg: insulin/glucagon/adrenaline)
binds to a specific receptor protein on the membrane of
target cell (eg: liver cell, muscle cell)
To form hormone-receptor complex (Hormone act as first
messenger)
This binding activates G-protein in the plasma membrane
Activated G-protein releases GDP
A new GTP binds to G protein, change its conformation
Which enable G-protein to bind with adenylyl cyclase
Which activates adenylyl cyclase to hydrolyse ATP to cAMP
(and PP)
i
• Non-steroid / hormone or amino acid based hormone cAMP act as second messenger inside the cell which activates
• Insoluble in lipid protein Kinase A that catalyzes phosphorylation process
• Cannot diffuse through the cell membrane
• Eg: insulin / epinephrine / glucagon Eg : In skeletal muscle, glucagon stimulate the breakdown of
glycogen to glucose
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