|MadSci Network: Biochemistry|
In researching your question, I came upon a great answer to a similar inquiry in the MadSci Network Biochemistry Archives. That question was a bit more complex, but the main idea was based on the possible effects of direct ATP injection.
As explained in an expertly detailed answer by Anthony Klon, free ATP faces several major barriers to its cellular uptake:
1) it's a high energy, very unstable molecule w/ an extremely short half-life extracellularly,
2) it's a fairly large molecule w/ a very high negative-charge on its tri-phosphate ligand, which are not favorable for crossing the plasma membrane by diffusion,
3) active transport requires expending chemical energy in the form of ATP itself, so the process would have to result in a sufficient net gain in intracellular ATP to be beneficial.
So to the best of my knowledge, there is no cellular
mechanism for the uptake of free ATP.
Thanks very much for your excellent question though,
Jeff Buzby, Ph.D.
CHOC Research Institute
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