DFF, a heterodimeric protein that functions downstream of caspase-3 to trigger DNA fragmentation during apoptosis.
We have identified and purified from HeLa cytosol a protein that induces DNA fragmentation in coincubated nuclei after it is activated by caspase-3. This protein, designated DNA Fragmentation Factor (DFF), is a heterodimer of 40 kDa and 45 kDa subunits. The amino acid sequence of the 45 kDa subunit, determined from its cDNA sequence, reveals it to be a novel protein. Caspase-3 cleaves the 45 kDa subunit at two sites to generate an active factor that produces DNA fragmentation without further requirement for caspase-3 or other cytosolic proteins. In cells undergoing apoptosis, the 45 kDa subunit is cleaved in the same pattern as it is cleaved by caspase-3 in vitro. These data delineate a direct signal transduction pathway during apoptosis: caspase-3 to DFF to DNA fragmentation.
Liu
X
X
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235, USA.
Zou
H
H
Slaughter
C
C
Wang
X
X
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D051017:Apoptosis Regulatory Proteins; D053148:Caspase 3; D020169:Caspases; D002460:Cell Line; D003001:Cloning, Molecular; D006224:Cricetinae; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D003600:Cytosol / Q000737:chemistry; D053938:DNA Fragmentation; D018076:DNA, Complementary / Q000235:genetics; D019281:Dimerization; D006367:HeLa Cells / Q000737:chemistry; D006801:Humans; D034882:Lamins; D008099:Liver; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009000:Monocytes / Q000166:cytology; D009687:Nuclear Proteins / Q000378:metabolism; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism / Q000502:physiology*; D017421:Sequence Analysis; D015398:Signal Transduction / Q000502:physiology
D051017:Apoptosis Regulatory Proteins; D018076:DNA, Complementary; D034882:Lamins; D009687:Nuclear Proteins; D011506:Proteins; C109664:caspase-activated DNase inhibitor; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases