Fig. 1
From: Targeting purinergic pathway to enhance radiotherapy-induced immunogenic cancer cell death
ATP release, receptors, and ectonucleotidases involved in purinergic signaling pathway. ATP is released into the extracellular space via exocytosis, transporters (for example, ABC), channels (for example, PANX-1), P2X7R, or cell lysis (for example, caused by irradiation). Once in the extracellular space, ATP acts at P2XR and P2YR, and is also hydrolyzed to ADP and AMP by ENTPDases such as CD39. ADP can activate P2Y12R and is hydrolyzed to AMP, which can be further hydrolyzed to ADO by CD73. CD73-generated ADO can bind to its P1 receptors (A1R, A2AR, A2BR, and A3R). ADO can be subsequently degraded to inosine by ADA, or transported into the intracellular space via NT. ABC, ATP-binding cassette; ADA, adenosine deaminase; ADO, adenosine; ADP, adenosine diphosphate; AMP, adenosine monophosphate; ATP, adenosine triphosphate; NT, nucleoside transporter; PANX-1, pannexin 1