Catalyzes the conversion of the nucleoside breakdown products ribose-1-phosphate and deoxyribose-1-phosphate to the corresponding 5-phosphopentoses. Catalyzes the interconversion of glucose-1-phosphate into glucose-6-phosphate but with a lower catalytic efficiency . In vitro, has also a low glucose 1,6-bisphosphate synthase activity which is most probably not physiologically relevant (, ).
Subcellular locations: Cytoplasm, Cytosol