Multiple Choice
The insulin receptor is an example of a _______:
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12. Biosignaling
Insulin Receptor
Multiple Choice
Which of the following is TRUE concerning the interaction between the insulin receptor and IRS-1:
A
The IRS protein phosphorylates the insulin receptor.
B
The β-subunits of the receptor bind to insulin, where each subunit has a separate insulin binding site.
C
Each β-subunit acts as a serine kinase and auto-phosphorylates the other subunit.
D
IRS is phosphorylated by the tyrosine kinase domains in the β-subunits of the insulin receptor.
E
IRS contains phosphorylated threonine residues that directly bind to insulin.
Verified step by step guidance1
Understand the role of the insulin receptor: The insulin receptor is a transmembrane receptor that is activated by insulin. It is composed of two α-subunits and two β-subunits.
Identify the function of the β-subunits: The β-subunits of the insulin receptor have intrinsic tyrosine kinase activity, which means they can phosphorylate tyrosine residues on target proteins.
Clarify the role of IRS-1: IRS-1 (Insulin Receptor Substrate 1) is a key signaling molecule that becomes phosphorylated on tyrosine residues by the activated insulin receptor.
Examine the interaction between the insulin receptor and IRS-1: Upon insulin binding, the β-subunits of the receptor undergo autophosphorylation, which activates their kinase activity. This leads to the phosphorylation of IRS-1 on specific tyrosine residues.
Conclude the correct statement: The correct interaction is that IRS-1 is phosphorylated by the tyrosine kinase domains in the β-subunits of the insulin receptor, facilitating downstream signaling pathways.
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