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. Author manuscript; available in PMC: 2017 Feb 1.
Published in final edited form as: Trends Cancer. 2016 Feb 1;2(2):95–109. doi: 10.1016/j.trecan.2016.01.003

Figure 1.

Figure 1

Structure and role of CD73 in the extracellular metabolic pathways.

CD73 is characterized by an N-terminal domain containing binding sites for zinc and cobalt ions and a C-terminal domain containing the AMP binding site. The C-terminal domain is linked to the plasma membrane through a GPI anchor. These two domains are connected by a short α helix. Once released in the extracellular milieu, ATP and ADP are converted into AMP via ecto enzyme CD39 and further into adenosine through CD73. Extracellular NAD+ is converted into ADPribose and nicotinamide (Nam) by NAD+-glycohydrolases and ADP ribosyl-transferases (ARTs). ADP ribose can be further split to form AMP by ADP-ribose pyrophosphatase, subsequently converted to adenosine by CD73. In addition, NAD+ can also be degradated by NAD+ diphosphatase to produce nicotinamide mononucleotide (NMN) and AMP.