Poly(ADP-ribose) polymerase-1 (PARP-1), a nuclear enzyme that catalyzes the NAD(+)-dependent addition of ADP-ribose polymers on a variety of nuclear proteins, has been shown to be associated with the nuclear matrix. As yet, the properties and conditions of this association are unclear. Here, vie show the existence of two PARP-1 pools associated with the nuclear matrix of rat liver and the ability of PARP-1 automodification to facilitate its binding to the nuclear matrix. (C) 2010 Elsevier Inc. All rights reserved.