PARP! - what does "PARP" do? (Apr/13/2005 )

Hi all,

Has anyone got any idea what PARP (poly ADP ribose polymerase) actually does in mammalian cells. I just need a quick, in short answer plz.

The enzyme is thought to have important function during apoptosis. However, with it has been difficult to establish where in the apoptotic cascade the enzyme is acting. There is evidence that the enzyme is involved in the stacking of polymers during DNA backbone formation , suggesting the enzyme ha a role in DNA damage repair and whether apoptosis is induced cell to die.

Histone and other nuclear poy-adp-ribosylation is linked to dammaged DNA. ADP come from NAD cofactor and chains of poly A can be over than 100A. This poly A accumulation modify the micro environment next dammage points and recruit enzymes like XRCC1 who mediates repair by NER mechanism.

Parp is a 113kd protein that can bind dna breaks. PArp2 can bind a abasic site.

Regarding apoptosis, PARP is degraded by caspase duing apoptosis/. This decrease the dna repair and enhance apoptosis signal (it's a balance between repairing and survive / apopotosis)

Moreover, during cell cycle, Parp proteins are localized in centromeres then next kinétochores, suggesting a role in regulation of mitosis checkpoint. In fact, an inactivation of PARP drive a desorganization of mitotic "fuseau" (i' sorry don't know the english translation for this term...)

i hope i'm not too long...
Fred

PRAP is a substrate of caspase-3 which is a central executor of apoptosis. that is all i know.

thanks guys