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Questions and Answers
The hormone, acting as the ______ messenger, binds to target cell membrane receptors coupled to a signal transducer called ____.
The hormone, acting as the ______ messenger, binds to target cell membrane receptors coupled to a signal transducer called ____.
first; g-protein
This signal transducer molecule, in turn, acts as an intermediary to activate the enzyme ______, which catalyzes the conversion of intracellular _____ to cyclic AMP.
This signal transducer molecule, in turn, acts as an intermediary to activate the enzyme ______, which catalyzes the conversion of intracellular _____ to cyclic AMP.
adenylate cyclase; ATP
Cyclic AMP then acts as the _____ messenger to initiate a cascade of reactions in the target cells.
Cyclic AMP then acts as the _____ messenger to initiate a cascade of reactions in the target cells.
second
Most of the subsequent events are mediated by the activation of enzymes called _______, which in turn activate or inactivate other enzymes by adding a ______ group to them.
Most of the subsequent events are mediated by the activation of enzymes called _______, which in turn activate or inactivate other enzymes by adding a ______ group to them.
The sequence of events initiated by the second messenger depends on the ______, _______, and ______.
The sequence of events initiated by the second messenger depends on the ______, _______, and ______.
In addition to messengers, including _____, ______, and ______.
In addition to messengers, including _____, ______, and ______.
Additionally, the ion ______ can act intracellularly as a second messenger in certain cases.
Additionally, the ion ______ can act intracellularly as a second messenger in certain cases.
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Study Notes
Second Messenger System Overview
- Cyclic AMP (cAMP) serves as a prominent example of a second messenger system.
- In this system, hormones function as first messengers, binding to receptors on target cell membranes.
- The binding of hormones activates G-proteins as signal transducers.
Role of Adenylate Cyclase
- G-proteins trigger the activation of the enzyme adenylate cyclase.
- Adenylate cyclase catalyzes the conversion of ATP (adenosine triphosphate) to cyclic AMP.
Function of Cyclic AMP
- Cyclic AMP acts as the second messenger within the cell.
- It initiates a cascade of biochemical reactions, influencing various cellular functions.
Protein Kinases and Their Function
- Subsequent cellular events are primarily mediated by protein kinases.
- Protein kinases modify other enzymes by adding phosphate groups, a process known as phosphorylation, which can activate or inactivate these enzymes.
Factors Influencing Second Messenger Action
- The outcome of the second messenger cascade is dependent on the target cell type, the availability of substrates, and the specific kinases activated.
- Multiple messengers can be involved alongside cAMP, such as diacylglycerol (DAG), inositol triphosphate (IP3), and cyclic GMP (cGMP).
Calcium as a Second Messenger
- Calcium ions can also function as intracellular second messengers in specific signaling pathways.
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