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Multiple Choice
What kinase phosphorylates IRS-1 in the insulin signaling pathway?
A
IRS-1 auto-phosphorylates itself.
B
PI3 Kinase.
C
PDK1.
D
The insulin receptor.
E
PKB.
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Verified step by step guidance
1
Understand the role of IRS-1 in the insulin signaling pathway. IRS-1 (Insulin Receptor Substrate 1) is a key protein that acts as a docking platform for downstream signaling molecules once it is phosphorylated.
Identify the initial step in the insulin signaling pathway. When insulin binds to its receptor, the insulin receptor undergoes autophosphorylation on its tyrosine residues.
Recognize the function of the insulin receptor. The insulin receptor is a tyrosine kinase, meaning it can transfer a phosphate group from ATP to a tyrosine residue on a substrate protein.
Determine the substrate for the insulin receptor. IRS-1 is phosphorylated by the insulin receptor on specific tyrosine residues, which allows it to recruit other signaling proteins.
Conclude that the insulin receptor is responsible for phosphorylating IRS-1. This phosphorylation is crucial for the propagation of the insulin signal through the pathway.