The cloning, genomic structure, localization, and expression of human deoxyribonuclease II?


Acidic endonuclease activity is present in all cells in the body and much of this can be attributed to the previously cloned and ubiquitously expressed deoxyribonuclease II (DNase II). Database analysis revealed the existence of expressed sequence tags and genomic segments coding for a protein with considerable homology to DNase II. This report describes the cloning of this cDNA, which we term deoxyribonuclease IIβ (DNase IIβ) and comparison of its expression to that of the originally cloned DNase II (now termed DNase IIα). The cDNA encodes a 357 amino acid protein. This protein exhibits extensive homology to DNase IIα including an amino-terminal signal peptide and a conserved active site, and has many of the regions of identity that are conserved in homologs in other mammals as well as C.elegans and Drosophila. The gene encoding DNase IIβ has identical splice sites to DNase IIα. Human DNase IIβ is highly expressed in the salivary gland, and at low levels in trachea, lung, prostate, lymph node, and testis, whereas DNase IIα is ubiquitously expressed in all tissues. The expression pattern of human DNase IIβ suggests that it may function primarily as a secreted enzyme. Human saliva was found to contain DNase IIα, but after immunodepletion, considerable acid-active endonuclease remained which we presume is DNase IIβ. We have localized the gene for human DNase IIβ to chromosome 1p22.3 adjacent (and in opposing orientation) to the human uricase pseudogene. Interestingly, murine DNase IIβ is highly expressed in the liver. Uricase is also highly expressed in mouse but not human liver and this may explain the difference in expression patterns between human and mouse DNase IIβ.

Publication Date


Journal Title




Digital Object Identifier (DOI)

Document Type