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. Author manuscript; available in PMC: 2013 Nov 27.
Published in final edited form as: Microbes Infect. 2012 May 23;14(10):10.1016/j.micinf.2012.05.005. doi: 10.1016/j.micinf.2012.05.005

Figure 1. Adenosine metabolism and signaling.

Figure 1

Cells release ATP in response to hypoxia and cell damage. The extracellular ATP is converted to adenosine (A) by the consecutive action of the ecto-nucleotidases, CD39 and CD73. The resulting adenosine can activate adenosine receptors (AR), be a substrate for extracellular adenosine deaminase (ADA), or reenter cells via equilibrative nucleoside transporters (ENTs). Within cells adenosine has multiple fates: 1) conversion to inosine via deamination, 2) conversion to adenosylhomocysteine (AdoHcy) via S-adenosylhomocytesine hydrolase (SAHH), or conversion to AMP by adenosine kinase (ADK). Adenosine can also be derived from AMP by the action of cytosolic 5’-nucleotidase (Cyto 5’NT).