An ecto-ATPase and an ecto-ATP diphosphohydrolase are expressed in rat brain.
Extracellular nucleotides acting as signaling molecules are inactivated by hydrolysis catalyzed by ecto-nucleotidases. ATP is sequentially degraded via ADP and AMP to adenosine. Enzymes that can be involved in the extracellular hydrolysis chain are ecto-ATP diphosphohydrolase (ecto-apyrase), ecto-ATPase, ecto-ADPase and 5'-nucleotidase. Mammalian ecto-ATP diphosphohydrolase is a member of a family of apyrases sharing four "apyrase conserved regions" that presumably participate in the formation of the catalytic site. We report the presence of ecto-ATP diphosphohydrolase in rat brain and the primary structure of a new mammalian member of the apyrase family. Expression in CHO cells shows that it represents an ecto-ATPase. As revealed by Northern analysis of rat tissues, the ecto-ATPase is co-expressed with ecto-ATP diphosphohydrolase in heart, kidney, spleen, thymus, lung, skeletal muscle and brain. Signals for both ecto-nucleotidases are very weak in liver. mRNAs for both proteins are present in PC12 cells, suggesting that the two nucleotidases may be co-expressed in the same neural cell. Using computer-aided sequence analysis, primary structure and membrane topography are compared with those of other members of the apyrase family.
Kegel
B
B
AK Neurochemie, Biozentrum der J. W. Goethe-Universität, Frankfurt am Main, Germany.
Braun
N
N
Heine
P
P
Maliszewski
C R
CR
Zimmermann
H
H
D000251:Adenosine Triphosphatases / Q000096:biosynthesis* / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001081:Apyrase / Q000096:biosynthesis* / Q000235:genetics; D001483:Base Sequence; D015152:Blotting, Northern; D001921:Brain / Q000201:enzymology*; D016466:CHO Cells; D002645:Chickens; D003001:Cloning, Molecular; D017124:Conserved Sequence; D006224:Cricetinae; D018076:DNA, Complementary / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010802:Phylogeny; D051381:Rats; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014162:Transfection
D018076:DNA, Complementary; D000251:Adenosine Triphosphatases; C027201:ectoATPase; D001081:Apyrase