title: Human placental ecto-5'-nucleotidase: isoforms and chemical crosslinking products of the membrane-bound and isolated enzyme.
abstract: Human placental ecto-5'-nucleotidase is specifically detected on Western blots using poly- or monoclonal antibodies. In two-dimensional electrophoresis 5'-nucleotidase, purified as well as membrane bound, is resolved in up to 13 isoforms distinguished by a different content of neuraminic acid. These forms span a range of molecular masses of about 67-71 kDa and of isoelectric points of 5.8-7.0. Chemical cross-linking of the purified enzyme with either homoor heterobifunctional reagents yields a dimer of about 140 kDa exclusively. On the other hand treatment of plasma membranes with the same reagents results in a crosslinking product of 5'-nucleotidase of about 97 kDa. The partner of the enzyme subunit in this crosslink, a protein of about 30 kDa, is unknown. Using specific antibodies the cytoskeletal components actin and tropomyosin were excluded as possible candidates.
authors.affiliation: Institut für Anthropologie und Humangenetik der Universität München.
authors.forename: S
authors.initials: S
authors.lastname: Buschette-Brambrink
authors.forename: W
authors.initials: W
authors.lastname: Gutensohn
mesh_terms: D015720:5'-Nucleotidase; D015153:Blotting, Western; D003432:Cross-Linking Reagents; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D007527:Isoenzymes / Q000302:isolation & purification*; D008565:Membrane Proteins / Q000302:isolation & purification*; D008970:Molecular Weight; D009438:Neuraminic Acids / Q000032:analysis; D009708:Nucleotidases / Q000302:isolation & purification*; D010920:Placenta / Q000201:enzymology*
chemical_list: D003432:Cross-Linking Reagents; D007527:Isoenzymes; D008565:Membrane Proteins; D009438:Neuraminic Acids; D009708:Nucleotidases; D015720:5'-Nucleotidase