Purine nucleoside enzyme that catalyzes the phosphorolysis of adenosine, guanosine and inosine nucleosides, yielding D-ribose 1-phosphate and the respective free bases, adenine, guanine and hypoxanthine (By similarity). Also catalyzes the phosphorolysis of S-methyl-5'-thioadenosine into adenine and S-methyl-5-thio-alpha-D-ribose 1-phosphate (By similarity). Also has adenosine deaminase activity (By similarity). Acts as a regulator of innate immunity in macrophages by modulating the purine nucleotide metabolism, thereby regulating the metabolic function and bioenergetic state of macrophages (PubMed:27478939, PubMed:31978345). Enables a purine nucleotide cycle between adenosine and inosine monophosphate and adenylosuccinate that prevents cytoplasmic acidification and balances the cytoplasmic-mitochondrial redox interface (PubMed:31978345). The purine nucleotide cycle consumes aspartate and releases fumarate in a manner involving fatty acid oxidation and ATP-citrate lyase activity (PubMed:31978345). Participates in pattern recognition receptor-induced cytokines in macrophages: associates with the NOD2-signaling complex and promotes optimal NOD2-induced signaling, cytokine secretion and bacterial clearance (By similarity). Localizes to the endoplasmic reticulum upon PRR stimulation of macrophages and associates with endoplasmic reticulum-stress sensors, promoting the endoplasmic reticulum unfolded protein response (UPR) (By similarity). Does not show laccase activity (By similarity). adenosine + phosphate = adenine + alpha-D-ribose 1-phosphate inosine + phosphate = alpha-D-ribose 1-phosphate + hypoxanthine guanosine + phosphate = alpha-D-ribose 1-phosphate + guanine phosphate + S-methyl-5'-thioadenosine = adenine + S-methyl-5-thio-alpha-D-ribose 1-phosphate adenosine + H(+) + H2O = inosine + NH4(+) Interacts with FASN. Interacts with SDHA. Interacts with ATF6, EIF2AK3 and ERN1. Upon stimulation of the pattern-recognition receptor (PRR) NOD2, localizes to the endoplasmic reticulum. Predominantly expressed in myeloid cells (PubMed:30510070). Highly expressed in primary macrophages and dendritic cells sorted from the peritoneum or spleen, respectively (at protein level) (PubMed:30510070). Phosphorylated on tyrosine residues. No visible phenotype in normal conditions (PubMed:30510070). Mice show increased inflammatory response in mouse models of arthritis and inflammation (PubMed:30510070). Belongs to the purine nucleoside phosphorylase YfiH/LACC1 family.