Multiple Choice
In the context of phosphorylation, how do protein kinases most directly affect the activity of enzymes?
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7. Enzyme Inhibition and Regulation
Phosphorylation
Multiple Choice
In the context of phosphorylation-based signal transduction, what is the primary role of activated protein kinases in a cell?
A
They remove phosphate groups from phosphorylated proteins to terminate signaling and restore baseline activity.
B
They synthesize from and inorganic phosphate during oxidative phosphorylation.
C
They bind DNA and directly regulate transcription by acting as sequence-specific transcription factors.
D
They catalyze the transfer of a phosphate group from to specific amino acid residues on target proteins, thereby altering the targets' activity, interactions, or localization.
Verified step by step guidance1
Understand that protein kinases are enzymes involved in phosphorylation, a key mechanism in signal transduction pathways.
Recognize that phosphorylation involves the transfer of a phosphate group, typically from ATP, to specific amino acid residues (such as serine, threonine, or tyrosine) on target proteins.
Recall that this phosphorylation event can change the target protein's activity, its ability to interact with other molecules, or its location within the cell, thereby modulating cellular responses.
Note that activated protein kinases do not remove phosphate groups; that function is performed by phosphatases, which terminate signaling.
Conclude that the primary role of activated protein kinases is to catalyze the transfer of phosphate groups from ATP to target proteins, which is essential for propagating and regulating cellular signals.
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