Cytosolic nucleoside phosphorylase (NP) trimer catalyzes the reversible reaction of guanosine or deoxyguanosine with orthophosphate to form guanine and ribose 1-phosphate or deoxyribose 1-phosphate (Ealick et al. 1990; Wiginton et al. 1980). While NP is active with either nuckeotide in vitro, levels of deoxyguanosine are normally low in vivo, limiting the extent of this reaction. NP deficiency in vivo is associated with defects in purine nucleotide salvage and leads to immunodeficiency (Williams et al. 1987).
|Reverse Reaction||guanine + (deoxy)ribose 1-phosphate <=> (deoxy)guanosine + orthophosphate [NP]|
|NP trimer||purine-nucleoside phosphorylase activity (0004731)|
|6771276||Characterization of purine nucleoside phosphorylase from human granulocytes and its metabolism of deoxyribonucleosides||J Biol Chem||1980|
|3029074||A human purine nucleoside phosphorylase deficiency caused by a single base change||J Biol Chem||1987|
|2104852||Three-dimensional structure of human erythrocytic purine nucleoside phosphorylase at 3.2 A resolution||J Biol Chem||1990|