Molecular characterization of a novel endonuclease (Xib) and possible involvement in lysosomal glycogen storage disorders.
We cloned and partially characterized a human endonuclease (Xib) which shows sequence homologies to pancreatic DNase I but an enzymatic activity closer to DNase II. We report on the structural differences found between Xib and other recently cloned human DNases. Fluores cence microscopy analysis of transiently transfected cells with Xib::pEGFP constructs indicate that the protein is located in the cytoplasm and possibly anchored to a membrane, as deduced from a hydrophobic amino acid stretch present at the C-terminal end. Xib is overexpressed in muscle and cardiac tissues and is alternately spliced in several normal and neoplastic cells. In situ hybridization studies using human cardiac and muscle biopsies indicate accumulation of Xib transcript in the vacuoles of muscle cells from patients affected by vacuolar myopathy as acid maltase deficiency; however, no point mutations were detected in their DNA.
Istituto Tecnologie Biomediche Avanzate-Consiglio Nazionale delle Ricerche, Via Fratelli Cervi 93, Segrate Milano, 20090, Italy.
G
G
Malferrari
U
U
Mazza
C
C
Tresoldi
E
E
Rovida
M
M
Nissim
M
M
Mirabella
S
S
Servidei
I
I
Biunno
D000595:Amino Acid Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D003001:Cloning, Molecular; D003850:Deoxyribonuclease I / Q000235:genetics*; D006008:Glycogen Storage Disease / Q000201:enzymology / Q000235:genetics*; D006367:HeLa Cells / Q000201:enzymology; D006801:Humans; D017403:In Situ Hybridization; D008247:Lysosomes / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics*; D018482:Muscle, Skeletal / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology; D016133:Polymerase Chain Reaction; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014162:Transfection
D009124:Muscle Proteins; D011993:Recombinant Fusion Proteins; C097585:DNASE1L1 protein, human; D003850:Deoxyribonuclease I