Simple glycolysis question

[zebalong]

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Sorry this is kind of basic but gunner in training states:

<LI id=lp-2362>In low glucose states, AMP &#8593; so cAMP &#8593; and protein kinase A inactivates PFK-2 by phosphorylating it, so PFK-1 activity drops and less F1,6BP is made
Which totally confuses me because AMP is an activator PFK-1 but what they are stating makes it look like it also overall inhibits the activity of PFK-1... can anyone help me with my confusion...

 

[bbydoc]

Sorry this is kind of basic but gunner in training states:

<LI id=lp-2362>In low glucose states, AMP &#8593; so cAMP &#8593; and protein kinase A inactivates PFK-2 by phosphorylating it, so PFK-1 activity drops and less F1,6BP is made
Which totally confuses me because AMP is an activator PFK-1 but what they are stating makes it look like it also overall inhibits the activity of PFK-1... can anyone help me with my confusion...

this only happens mainly in the liver (gluconeogenesis) under the influence of glucagon.
while this is true AMP &#8593; and cAMP &#8593; this is not AMP &#8593; so cAMP &#8593;. cAMP increases in response to glucagon not AMP, Im 96% certain so feel free to comment anyone.

 

[futuredoctor10]

this only happens mainly in the liver (gluconeogenesis) under the influence of glucagon.
while this is true AMP &#8593; and cAMP &#8593; this is not AMP &#8593; so cAMP &#8593;. cAMP increases in response to glucagon not AMP, Im 96% certain so feel free to comment anyone.

Yeah I believe glucagon binding to cell surface receptors results in activation of adenylyl cyclase and thus increased cAMP levels result:
the increase in cAMP then activates PKA.

However, AMP levels rising will help activate AMP-activated protein kinase (aka) AMPK. This enzyme regulates many of the enzymes in fed/fasting state, and I believe this includes PFK (not 100% sure). Protein Kinase A is activated by cAMP and is separate.

 

[DuxburyPembroke]

Yeah I believe glucagon binding to cell surface receptors results in activation of adenylyl cyclase and thus increased cAMP levels result:
the increase in cAMP then activates PKA.

This is true. it's a GPCR, and glucagon binding activates adenylate cyclase, which activates PKA which starts the phosphorylation cascade that brings the cell into the "glucagon world". Norepinephrine has the same sort of transduction (it helps me remember, anyway).

 

[bbydoc]

This is true. it's a GPCR, and glucagon binding activates adenylate cyclase, which activates PKA which starts the phosphorylation cascade that brings the cell into the "glucagon world". Norepinephrine has the same sort of transduction (it helps me remember, anyway).

not quite correct, norepinephrine has different signal transduction mechanisms depending on the type of adrenergic receptors (alpha1: phospholipase c and beta: adenylyl cyclase).

anyway, we are digressing from the original point, sorry OP.

 

[zebalong]

Thanks! Now i get it =)