Ecto-5-prime-nucleotidase catalyzes conversion at neutral pH of purine 5-prime mononucleotides to nucleosides. The enzyme consists of a dimer of 2 identical 70 kD subunits tethered by a glycosyl phosphatidyl inositol moeity to the exterior plasma membrane surface. The enzyme, a marker of lymphocyte differentiation is associated in deficiency with a variety of immunodeficiency diseases. The preferred substrate is AMP. The NT5 gene has been localized to 6q14-q21 by immunofluorescence and a study of a panel of human x mouse hybrids that contained fragments of chromosome 6 as translocations.

2-8°C (short-term); -20°C (long-term)