Protein kinase a

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In cell biology, Protein kinase A (PKA) refers to a family of enzymes whose activity is dependent on cellular levels of cyclic AMP (cAMP). PKA is also known as cAMP-dependent protein kinase (EC 2.7.11.11). Protein kinase A has several functions in the cell, including regulation of glycogen, sugar, and lipid metabolism.

It should not be confused with AMP-activated protein kinase - which, although being of similar nature, may have opposite effects - [1] nor with cyclin-dependent kinases (Cdks), nor with the acid dissociation constant, pKa.
Activation

Each PKA is a holoenzyme that consists of a regulatory subunit dimer with each regulatory subunit being bound to a catalytic subunit. Under low levels of cAMP, the holoenzyme remains intact and is catalytically inactive. When the concentration of cAMP rises (e.g., activation of adenylate cyclases by G protein-coupled receptors coupled to Gs, inhibition of phosphodiesterases that degrade cAMP), cAMP binds to the two binding sites on the regulatory subunits, which leads to the release of the catalytic subunits. For maximal function, each catalytic subunit must also be phosphorylated, which occurs on Thr 197 and helps orientate catalytic residues in the active site.[2]

1. Cytosolic cAMP increases. 2. Two cAMP molecules bind to each PKA regulatory subunit. 3. The regulatory subunits move out of the active sites of the catalytic subunits and the R2C2 complex dissociates 4. The free catalytic subunits interact with proteins to phosphorylate Ser or Thr residues. Source of the article published in description is Wikipedia. I am sharing their material. © by original content developers of Wikipedia.

[luckycharms]

Great review.  The only thing I would add is that the concentration of cAMP is high when glucose level is low in the blood.  This triggers the liver to create glucose to send into the blood.  Glycogen is broken down to G-1-P in order for glucose to be made through gluconeogenesis.  In the heart and other muscles, the G-1-P would be used for glycolysis, like Suman said in the video.

[neil]

Very good tutorial, thank you for doing this Suman.