ADP-Ribosylation of Nuclear Matrix Proteins. Association of Poly(ADP-Ribose) Synthetase with the Nuclear Matrix

Abstract

The residual structures which remain after DNase digestion and high salt extraction of isolated nuclei, are termed nuclear matrices [1]. The nuclear matrix contains the structural elements of the peripheral lamina, the pore complexes, the nucleoli, and an internal fibrogranular network, and is considered to represent the main structural framework of the interphase nucleus. The DNA loops appear to be attached to the matrix at specific binding sites [2, 3]. Moreover, it was observed that basic biochemical reactions occur in tight association with this solid support. Thus, DNA replication is considered to proceed in association with the nuclear matrix [4, 5]. Furthermore, actively transcribed genes were found enriched in the nuclear matrix [6, 7]. It was observed that RNA synthesis and processing proceed in association with the matrix [8, 9] which may also play a role in certain transport processes [10]. Binding of steroid hormones [11] and of viral proteins [12] by the nuclear matrix and modification of matrix proteins by phosphorylation have been described [13, 14]. (For reviews, see [15, 16]).