Multiple Choice
What could be the result of a mutation in the R subunits of cAMP-dependent protein kinase A (PKA) that inhibits formation of the R2C2 protein complex?
12. Biosignaling
cAMP & PKA
Struggling with Biochemistry?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Which of the following statements about protein kinase A (PKA) is false?
A
PKA binds a total of four molecules of cAMP, two molecules on each of the regulatory (R) subunits.
B
PKA binds a total of four molecules of cAMP, one on each of the four subunits.
C
Once active, the catalytic (C) subunits dissociate and phosphorylate target proteins.
D
When inactive, PKA is a tetramer of two regulatory (R) and two catalytic (C) subunits.
Verified step by step guidance1
Understand the structure of Protein Kinase A (PKA): PKA is composed of two regulatory (R) subunits and two catalytic (C) subunits, forming a tetramer when inactive.
Learn how PKA is activated: PKA becomes active when cAMP binds to the regulatory subunits. Each regulatory subunit binds two molecules of cAMP, totaling four molecules for the entire PKA complex.
Recognize the role of cAMP: The binding of cAMP to the regulatory subunits causes a conformational change that releases the catalytic subunits, activating them.
Identify the function of the catalytic subunits: Once released, the catalytic subunits phosphorylate specific target proteins, which is a key mechanism in signal transduction pathways.
Evaluate the false statement: The statement 'PKA binds a total of four molecules of cAMP, one on each of the four subunits' is incorrect because cAMP binds only to the regulatory subunits, not the catalytic subunits.
Related Videos
Related Practice
