You have discovered a new gene that encodes an unusual regulatory subunit of PKA, which you name Ro. As with the R2C2 version of PKA, Ro forms a dimer and interacts with two molecules of the same catalytic subunit (C) found in PKA to form a Ro2C2 heterotetramer. However, unlike the R in conventional PKA, each Ro subunit binds 8 molecules of cAMP. Which of the following properties would you predict Ro C2 PKA would display compared to the conventional RC2 form of PKA? a. PKA with Ro subunits would become active at a lower concentration of cAMP. b. Full activity of PKA with Ro subunits would occur at a higher concentration of CAMPc. The dynamic range of activity of PKA with Ro subunits would occur over a narrower range of cAMP concentration. d. The dynamic range of activity of PKA with Ro subunits would over a wider range of cAMP concentration

Question

Biology

Emilie Bauer

22 October, 07:48

You have discovered a new gene that encodes an unusual regulatory subunit of PKA, which you name Ro. As with the R2C2 version of PKA, Ro forms a dimer and interacts with two molecules of the same catalytic subunit (C) found in PKA to form a Ro2C2 heterotetramer. However, unlike the R in conventional PKA, each Ro subunit binds 8 molecules of cAMP. Which of the following properties would you predict Ro C2 PKA would display compared to the conventional RC2 form of PKA? a. PKA with Ro subunits would become active at a lower concentration of cAMP. b. Full activity of PKA with Ro subunits would occur at a higher concentration of CAMPc. The dynamic range of activity of PKA with Ro subunits would occur over a narrower range of cAMP concentration. d. The dynamic range of activity of PKA with Ro subunits would over a wider range of cAMP concentration

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Nemo · Answer 1

Compared to the conventional RC2 form of PKA, Ro C2 PKA would display the following properties:

PKA with Ro subunits would become active at a lower concentration of cAMP.

Full activity of PKA with Ro subunits would occur at a higher concentration of cAMP - Correct Option.

The dynamic range of activity of PKA with Ro subunits would occur over a narrower range of cAMP concentration.

The dynamic range of activity of PKA with Ro subunits would over a wider range of cAMP concentration.

Explanation:

In the presence of high levels of cAMP the conventional R2C2 form of PKA (R2C2 complex) splits into an R2 subunit and two C subunits. Two cAMP molecules bind to the regulatory sites of the complex. However, each Ro regulatory subunit binds 8 molecules of cAMPin the new gene product. Each regulatory subunit has a distinct binding site for cAMP. Thus, full activity of PKA with Ro subunits would occur at a higher concentration of cAMP inasmuch cAMP binding to regulatory subunits exhibit positive cooperativity,.