Travis
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- Jul 14, 2016
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The main signal might be ATP phosphorylation of alcoholic sidechains (Tyr, Thr, Ser). Tyrosine phosphorylation seems especially interesting since it is stabilized by resonance. The conjugated π-bond system would be expected to help with signal transduction (e⁻), especially if tyrosine's β-carbon were deprotonated forming another conjugated double bond.
The resonance also stabilizes the phenylate ion making this reaction easily reversible.
Tyrosine phosphorylation: thirty years and counting
Phosphate would certainly change the c-value, and may even act as an all-out electron donor.
It is well-known that serine can be phosphorylated too. This is, after all, how organophosphates paralyze. The target for acetylcholine esterase inhibition is serine.
Lysine of course can be phosphorylated too.
No high-energy phosphate bonds required. I think ATP works it's magic mainly by phosphorylating proteins, especially tyrosine. Lysine has a long and saturated side-chain that would seem to isolate it from the peptide backbone.
Phosphorylation | Thermo Fisher Scientific
The resonance also stabilizes the phenylate ion making this reaction easily reversible.
In discussions about the evolution of tyrosine phosphorylation, a common question is “Why tyrosine?”. Like Ser/Thr phosphate esters, the P.Tyr phosphate ester linkage has a relatively high bond energy, and the equilibrium constant for most protein kinases is close to 1, meaning that kinases can catalyze the reverse reaction in the presence of ADP and remove phosphate from the phosphorylated residue in a target protein to generate ATP. Perhaps the major reason why P.Tyr was selected is that the SH2 domain binding energy for a P.Tyr residue is higher than that for P.Ser or P.Thr, because of the contribution of contacts that can be made with the phenolic ring in addition to interactions with the phosphate [...] P.Tyr residues have a very short half life, unless protected by binding to SH2/PTP domains.
Tyrosine phosphorylation: thirty years and counting
Phosphate would certainly change the c-value, and may even act as an all-out electron donor.
It is well-known that serine can be phosphorylated too. This is, after all, how organophosphates paralyze. The target for acetylcholine esterase inhibition is serine.
Lysine of course can be phosphorylated too.
No high-energy phosphate bonds required. I think ATP works it's magic mainly by phosphorylating proteins, especially tyrosine. Lysine has a long and saturated side-chain that would seem to isolate it from the peptide backbone.
Phosphorylation | Thermo Fisher Scientific