title: Evidence for alternative splicing of ecto-ATPase associated with termination of purinergic transmission.
abstract: Ectonucleotidases provide the signal termination mechanism for purinergic transmission, including fast excitatory neurotransmission by ATP in the CNS. This study provides evidence for ectonucleotidase expression in the rat cochlea, brain and other tissues. In addition to detection of rat ecto-ATPase and ecto-ATPDase in these tissues, we identify a novel ecto-ATPase splice variant arising from the loss of a putative exon (193 bp) in the C-terminal coding region. This is the first evidence of alternative splicing in the ecto-ATPase gene family. Splicing of the 193-bp putative exon containing a stop codon extends the open reading frame and provides translation of an additional 50 amino acids compared with the isoform isolated earlier from the rat brain (rEATPase(A); GenBank accession #Y11835). The splice variant (rEATPase(B); GenBank accession #AF129103) encodes 545 amino acids with a predicted protein molecular mass of 60 kDa. rEATPase(B) contains a long cytoplasmic tail (62 amino acids) with three potential protein kinase CK2 phosphorylation sites not present in rEATPase(A). Co-expression of two ecto-ATPase isoforms with different regulatory sites suggests that the extracellular ATP signal levels may be differently influenced by intracellular feedback pathways.
authors.affiliation: Faculty of Medicine and Health Science, Department of Physiology, The University of Auckland, Private Bag 92019, Auckland, New Zealand.
authors.forename: S M
authors.initials: SM
authors.lastname: Vlajkovic
authors.forename: G D
authors.initials: GD
authors.lastname: Housley
authors.forename: D
authors.initials: D
authors.lastname: Greenwood
authors.forename: P R
authors.initials: PR
authors.lastname: Thorne
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000502:physiology; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001081:Apyrase / Q000235:genetics; D001483:Base Sequence; D003051:Cochlea / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic; D007527:Isoenzymes / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011983:Receptors, Purinergic / Q000502:physiology*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D009435:Synaptic Transmission; D014018:Tissue Distribution
chemical_list: D007527:Isoenzymes; D012333:RNA, Messenger; D011983:Receptors, Purinergic; D000251:Adenosine Triphosphatases; C027201:ectoATPase; D001081:Apyrase