Article

Purification, Cloning, and Expression of an Apyrase from the Bed Bug Cimex lectularius

Medical Entomology Section, Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892-0425, USA.
Journal of Biological Chemistry (Impact Factor: 4.6). 11/1998; 273(46):30583-30590.

ABSTRACT An enzyme that hydrolyzes the phosphodiester bonds of nucleoside tri- and diphosphates, but not monophosphates, thus displaying
apyrase (EC 3.6.1.5) activity, was purified from salivary glands of the bed bug, Cimex lectularius. The purifiedC. lectularius apyrase was an acidic protein with a pI of 5.1 and molecular mass of ∼40 kDa that inhibited ADP-induced platelet aggregation
and hydrolyzed platelet agonist ADP with specific activity of 379 units/mg protein. Amplification of C. lectulariuscDNA corresponding to the N-terminal sequence of purified apyrase produced a probe that allowed identification of a 1.3 kilobase
pair cDNA clone coding for a protein of 364 amino acid residues, the first 35 of which constituted the signal peptide. The
processed form of the protein was predicted to have a molecular mass of 37.5 kDa and pI of 4.95. The identity of the product
of the cDNA clone with nativeC. lectularius apyrase was proved by immunological testing and by expressing the gene in a heterologous host. Immune serum made against
a synthetic peptide with sequence corresponding to the C-terminal region of the predicted cDNA clone recognized bothC. lectularius apyrase fractions eluted from a molecular sieving high pressure liquid chromatography and the apyrase active band from chromatofocusing
gels. Furthermore, transfected COS-7 cells secreted a Ca2+-dependent apyrase with a pI of 5.1 and immunoreactive material detected by the anti-apyrase serum.C. lectularius apyrase has no significant sequence similarity to any other known apyrases, but homologous sequences have been found in the
genome of the nematode C. elegansand in mouse and human expressed sequence tags from fetal and tumor EST libraries.

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