CD73 (Ecto-5-prime-nucleotidase, 5-prime-ribonucleotide phosphohydrolase) catalyzes the conversion at neutral pH of purine 5-prime mononucleotides to nucleosides, the preferred substrate being AMP. CD73 consists of a dimer of 2 identical 70 kDa subunits bound externally to the plasma membrane by a glycosyl phosphatidyl inositol linkage. CD73 is used as a marker of lymphocyte differentiation. Consequently, a deficiency of CD73 occurs in a variety of immunodeficiency diseases. Other forms of 5-prime nucleotidase exist in the cytoplasm and lysosomes and can be distinguished from CD73 by their substrate affinities, requirement for divalent magnesium ion, activation by ATP, and inhibition by inorganic phosphate. The CD73 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. Defects in the CD73 gene can lead to the calcification of joints and arteries, and intestinal tuberculosis. Two transcript variants encoding different isoforms of CD73 have been found.
5'-NT; 5'-nucleotidase; 5'-nucleotidase, ecto (CD73); CD73; Ecto-5'-nucleotidase; Purine 5-Prime-Nucleotidase