Cloning, expression, and characterization of a soluble @entity460 -activated nucleotidase, a XXXX enzyme belonging to a new family of extracellular nucleotidases.

@entity1 @entity3007 @entity1423 @entity858 @entity377 @entity856 @entity3006 @entity460 @entity857 @entity20559 @entity855
The salivary apyrases of blood-feeding arthropods are @entity377 -hydrolyzing enzymes implicated in the inhibition of host @entity1423 through the hydrolysis of extracellular @entity857 . A @entity1 cDNA homologous to the apyrase cDNA of the blood-feeding bed bug was identified, revealing an open reading frame encoding a 371-amino acid protein. A cleavable signal peptide generates a secreted protein of 333 residues with a predicted core molecular mass of 37,193 Da. Expression in COS-1 cells produced a secreted apyrase in the cell media. The ADPase and ATPase activities were dependent upon @entity460 , with a pH optimum between pH 6.2 and 7.2. Interestingly, the preferred substrate was not @entity857 , as might be expected for an enzyme modulating @entity1423 , but rather @entity858 , followed by @entity3006 , @entity856 , @entity3007 , @entity857 , and @entity855 . The nucleotidase did not hydrolyze @entity20559 . Size-exclusion chromatography and Western blot analysis revealed a molecular mass of approximately 34-37 kDa. Treatment of the enzyme with peptide N-glycosidase F indicated that the protein is glycosylated. Northern analysis identified the transcript in a range of @entity1 tissues, including testis, placenta, prostate, and lung. No traditional apyrase-conserved regions or @entity377 -binding domains were identified in this @entity1 enzyme, indicating membership in a new family of extracellular nucleotidases.
