Talk:Protein kinase A
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Confusion with PRKAR2A
I recently made an article on the PRKAR2A gene using content from ProteinBoxBot. I'm trying to add wikilinks and the article makes reference to "cAMP-dependent protein kinase (AMPK)." However, I find articles on Wikipedia for both AMPK and cAMP-dependent protein kinase. I know next to nothing about this field of biology and would be very appreciative if someone who knows better and I could sort this all out. Forluvoft (talk) 02:58, 29 November 2007 (UTC)
Consfusion with phosphorylation
"Protein Kinase A acts to phosphorylate many enzymes important in metabolism. Protein kinase A phosphorylates Acetyl-CoA carboxylase and pyruvate dehydrogenase. Allosteric regulation of these enzymes in such a manner has an inhibitory effect. Insulin will increase the level of phosphorylation of these enzymes, which will divert acetyl-coA down the lipogenesis pathway."
Obviously this makes no sense, if phosphorylation of Acetyl-CoA carboxylase would have an inhibitory effect, that would mean less lipogenesis! (PKA probably dephosporylates Acetyl-Coa carboxylase) —Preceding unsigned comment added by 126.96.36.199 (talk) 09:57, 26 September 2008 (UTC)
- As noted in my recent edit, they are distinct enzymes, and should have separate articles. Mikael Häggström (talk) 08:42, 31 May 2009 (UTC)
PRKAR2A is the gene name for the alpha2 encoded subunit of Protein Kinase A. This protein is cyclic-AMP dependent and has a range of different effects on metabolism, as cAMP is an important second messenger. PKA has subunits other than alpha.
AMPK alpha 2, encoded by the gene PRKAA2, is the alpha 2 subunit of AMP-dependent protein kinase A. This protein is AMP-dependent and also has a range of different effects on metabolism, as AMP is a signal to the cell that energy is low and the cell needs to make more, via ATP producing mechanisms. AMPK has three subunits: alpha, beta, and gamma.
These AMPK and PKA proteins are not the same, and are inaccurately being described as in the same family. They are both kinases, and therefore they phosphorylate their target proteins. However, they are encoded by different genes, and have different targets.
Therefore, PKA and AMPK articles should NOT be merged.
Furthermore, the sentence in the Phosphorylation Confusion section: "Insulin will increase the level of phosphorylation of these enzymes, which will divert acetyl-coA down the lipogenesis pathway" is incorrect, as the updated comment suggests. Increased phosphorylation of ACC results in enzyme inhibition and less of production of malonyl-CoA, which results in reduced lipogenesis. Lipogenesis can only be active when ACC is active, in the hypo-phosphorylated state. However, to clarify, a kinase can only phosphorylate, never dephosphorylate. Phosphotases are the enzymes responsible for dephosphorylation.
- My proposal is not to merge PRKAR2A with AMPK, I agree these two protein are in different families. The problem with the PRKAR2A article is that it states "cAMP exerts its effects by activating the cAMP-dependent protein kinase (AMPK)". Which implies AMPK and cAMP-dependent protein kinase should point to the same article, but they dont. My original proposal to solve this was to merge cAMP-dependent protein kinase (which redirects to Protein kinase A) with AMPK (which redirects to AMP-activated protein kinase). I've had a bit more time to look into this now and I disagree with my own merge suggestion. AMPK is distinct from protein kinase A and should be kept so. I believe the misleading line in the PRKAR2A article should read "cAMP exerts its effects by activating the AMP-activated protein kinase (AMPK)". I'll add this correction to the PRKAR2A article unless told otherwise. K.murphy (talk) 13:05, 20 November 2008 (UTC)
6PF-2-K/Fru-2,6-P2ase and PK isoforms in muscle/liver
I agree that AMPK and PKA articles should not me merged.
On another note: Recent research suggest there are tissue specific variants of the two glycolytic enzymes, the bifunctional 6PF-2-Kinase/2,6Phosphatase and Pyruvate kinase. The skeletal muscle isoforms actually lack a PKA phosphorylation site hence cAMP levels do not affect them. So PKA does not inhibit glycolysis, in fact glucose is released from glycogen in response to rising cAMP. Which makes sense as e.g. adrenalin binding acts via the PKA pathway and as we know adrenalin stimulates the use of glucose. In contrast with liver where glycolysis is inhibited in response to cAMP rise. The relevant sections should be corrected. —Preceding unsigned comment added by 188.8.131.52 (talk) 19:51, 26 May 2009 (UTC)
The functions list are too limitted and could be misleading.
I bumped on this page and read through what has been presented. I surprisely realized that the PKA related page even does not mention its role in fight-and-flight response, including the change of the cardiovascular function. In the history, PKA was the first kinase to be discovered because of the research on this response. I would urge the Wilkipedia to add this on. —Preceding unsigned comment added by 184.108.40.206 (talk) 04:22, 12 September 2009 (UTC)