5′-nucleotidase (EC 3.1.3.5) can catalyze the hydrolysis of most ribonucleoside 5′-monophosphates and deoxynucleoside 5′-monophosphates to the corresponding nucleosides and orthophosphates. It is localized predominantly in the plasma membranes of human and animal tissues,and often used as a marker enzyme for plasma membranes in