Enables purine-nucleoside phosphorylase activity. Predicted to be involved in several processes, including nucleoside catabolic process; nucleotide metabolic process; and positive regulation of interleukin-2 production. Predicted to act upstream of or within inosine catabolic process; positive regulation of T cell activation; and urate biosynthetic process. Located in extracellular region. Human ortholog(s) of this gene implicated in purine nucleoside phosphorylase deficiency and purine-pyrimidine metabolic disorder. Orthologous to human PNP (purine nucleoside phosphorylase); PARTICIPATES IN adenine phoshoribosyltransferase deficiency pathway; adenosine monophosphate deaminase deficiency pathway; adenylosuccinate lyase deficiency pathway; INTERACTS WITH 17alpha-ethynylestradiol; 2,3,7,8-Tetrachlorodibenzofuran; 4,4'-sulfonyldiphenol.