The cDNA cloning of human placental ecto-ATP diphosphohydrolases I and II.
The cDNA clones of two isoforms (enzymes I and II) of human placental ecto-ATP diphosphohydrolases have been isolated based on the N-terminal amino acid (aa) sequence of the immunopurified 82 kDa protein and characterized. The cDNA clone encoding enzyme I consists of 2081 nucleotides and the predicted enzyme I consists of 517 aa residues. Enzyme I has a 5'-UTR and an N-terminal 11 aa sequence that differ from CD39, but the rest of the sequence is the same as CD39. The hydropathy plot indicated that enzyme I has two hydrophobic regions near the N- and C-termini of the molecule. In contrast, enzyme II consists of 1814 nucleotides and the predicted protein consists of 306 aa residues. The sequence of 1-1018 nucleotides of enzyme II is identical to that of enzyme I, but the 1019-1814 nucleotide sequence is different from both enzyme I and CD39. The hydropathy plot indicated that enzyme II has one hydrophobic region near the N-terminus, suggesting that enzyme II is also anchored to the cell membrane. It is, however, likely that some of enzyme II exists as a soluble form in plasma, possibly after proteolytic processing.
Second Department of Internal Medicine, Nara Medical University, Kashihara, Japan.
M
M
Matsumoto
Y
Y
Sakurai
T
T
Kokubo
H
H
Yagi
K
K
Makita
T
T
Matsui
K
K
Titani
Y
Y
Fujimura
N
N
Narita
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D015703:Antigens, CD / Q000235:genetics; D001081:Apyrase / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004730:Endothelium, Vascular / Q000201:enzymology; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000235:genetics*; D008969:Molecular Sequence Data; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D011487:Protein Conformation; D017422:Sequence Analysis, DNA
D015703:Antigens, CD; D018076:DNA, Complementary; D007527:Isoenzymes; D000251:Adenosine Triphosphatases; C027201:ectoATPase; D001081:Apyrase; C067869:CD39 antigen