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. Author manuscript; available in PMC: 2023 Jun 24.
Published in final edited form as: Pharmacol Ther. 2022 Oct 22;240:108300. doi: 10.1016/j.pharmthera.2022.108300

Table 1.

Adenosine Transport Characteristics of ENTs and CNTs

Nucleoside Transporter Solute Carrier Family Adenosine Affinity [Km (mM)] Tissue Distribution Subcellular Localization Reference
CNT1 SLC28A1 -- Small intestine, Kidney, Liver, Plasma membrane (Gray, et al., 2004; J. D. Young, et al., 2013)
CNT2 SLC28A2 0.008 Small intestine, Testis, skeletal muscle, liver, kidney, intestine, pancreas, placenta, brain Plasma membrane (Duflot, et al., 2004; Gray, et al., 2004; Pastor-Anglada & Perez-Torras, 2018a, 2018b; J. D. Young, et al., 2013)
CNT3 SLC28A3 0.0024–0.015 Mammary gland, pancreas, bone marrow, trachea, intestine Plasma membrane, sometimes intracellular (Pastor-Anglada & Perez-Torras, 2018a, 2018b; J. D. Young, et al., 2013)
ENT1 SLC29A1 0.04–0.78 Widely expressed with high levels in skeletal and smooth muscle, lung, thymus Plasma, nuclear, and mitochondrial membranes (Parkinson, et al., 2011; Ward, Sherali, Mo, & Tse, 2000)
ENT2 SLC29A2 0.14–0.78 Widely expressed, especially skeletal muscle Plasma and nuclear membranes (Parkinson, et al., 2011; Ward, et al., 2000)
ENT3 SLC29A3 0.78–1.86 Widely expressed in most tissues Endosomal, lysosomal, and mitochondrial membranes (Baldwin, et al., 2005; Kang, et al., 2010; Parkinson, et al., 2011; Pastor-Anglada & Perez-Torras, 2018a, 2018b; Rahman, Askwith, & Govindarajan, 2017)
ENT4 SLC29A4 0.78 Heart, brain, skeletal muscle Plasma membrane (Barnes, et al., 2006; Parkinson, et al., 2011; Pastor-Anglada & Perez-Torras, 2018a)