High impact information on ENTPD8

• The deduced primary sequence of the chicken oviduct ecto-ATPDase indicates a protein of 493 amino acid residues with a molecular mass of 54 kDa [1].
• We have examined the in vivo localization of extracellular ecto-ATPase and ecto-apyrase (ATPDase) in adult chicken gizzard and stomach by immunofluorescence and laser scanning confocal microscopy [2].
• We also partially purified the ecto-apyrase of chicken stomach, an 80-kDa membrane glycoprotein [2].
• However, ecto-ATPase was clustered in the sarcolemma of the organized layer of circular smooth muscle and in smooth muscle cells of the septa surrounding the glandular tissue, but not in the glandular cells containing the ecto-apyrase [2].
• We previously demonstrated that the major ecto-nucleoside triphosphate phosphohydrolase in the chicken liver membranes is an ecto-ATP-diphosphohydrolase (ecto- ATPDase) [Caldwell, C., Davis, M.D. & Knowles, A.F. (1999) Arch. Biochem. Biophys. 362, 46-58] [3].

Anatomical context of ENTPD8

• Anti-ecto-apyrase antibody detected a single 80-kDa band (putative apyrase) in Western blots of both chicken gizzard membrane extracts and partially purified anion exchange fractions, but the antibody did not detect ecto-apyrase in immunolabeled gizzard cryosections [2].
• The stimulation of the expressed liver ecto-ATPDase by detergents indicates that this property is intrinsic to the enzyme protein, and cannot be attributed to the lipid environment of the native membranes [3].
• Immunochemical staining demonstrates the distribution of the ecto-ATPDase in the bile canaliculi of the chicken liver [3].
• Ecto-enzymes capable of hydrolyzing ATP and ADP (NTPDase) are present in the central nervous system of various species [4].

Associations of ENTPD8 with chemical compounds

• Compounds that inhibit some ion-motive ATPases, e.g., sulfhydryl reagents, xanthene derivatives, NBD-halides, and suramin, also inhibit the gizzard ecto-ATPase, but not another E-ATPase, the chicken liver ecto-ATP-diphosphohydrolase, which contains the same conserved regions as the ecto-ATPase [5].
• Ouabain had no effect on the NTPDase-like activity of fish, chickens or rats [6].
• NTPDase activity was decreased in the presence of lanthanum in the chicken (ADP) and rat (ATP and ADP) liver [6].
• Orthovanadate (0.1-0.3 mM) only inhibited fish synaptosomal NTPDase [4].
• Trifluoperazine (0.05-0.2 mM) and suramin (0.03-0.3 mM) inhibited NTPDase at all concentrations tested [6].

Analytical, diagnostic and therapeutic context of ENTPD8

• Molecular cloning of the chicken oviduct ecto-ATP-diphosphohydrolase [1].
• The primary sequence of the liver ecto-ATPDase deduced from its cDNA obtained by RT-PCR cloning also shows only minor differences from that of the oviduct ecto-ATPDase [3].
• This antibody is specific for the ecto-ATPases, since the more abundant chicken stomach ecto-apyrase is not recognized in immunoprecipitation, western blot or immunolocalization analyses [7].

References