Poly (ADP-ribose) polymerase (PARP) is a 113kDa
nuclear protein that is involved in DNA repair and is an early
marker of apoptosis. PARP is activated by DNA strand breaks to
produce poly (ADPribose) polymers and attach them to nuclear proteins
such as histone, topoisomerase, DNA-dependent Protein kinase,and
itself. PARP contains an amino terminal zinc-finger containing-DNA
binding domain, an automodification domain and a carboxyl-terminal
catalytic domain. Upon induction of apoptosis in HL-60 cells treated
with etoposide, PARP is cleaved by caspase between Asp 214 and
Gly-215 into an 85kDa and a 29kDa fragment. PARP-knock out mice
display no phenotypic abnormalities, and apoptosed normally in
response to TNF, ?-radiation, dexamethasone, suggesting PARP is
dispensable for apoptosis.
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