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Nuclear matrix-associated poly(ADPribosyl)ation system in rat testis chromatin
P Quesada1, M d'Erme, G Parise
1Dipt. Chimica Organica e Biologica, Università Federico II di Napoli, Italy.
Experimental Cell Research
|September 1, 1994
Summary
Poly(ADP-ribose) polymerase in rat testis chromatin was studied. This enzyme modifies histone-like proteins in chromatin loops and nuclear matrix.
Area of Science:
- Molecular Biology
- Biochemistry
- Cell Biology
Background:
- Poly(ADP-ribose) polymerase (PARP) plays a critical role in DNA repair and chromatin remodeling.
- Understanding PARP localization and activity within specific nuclear compartments is crucial for elucidating its functions.
Purpose of the Study:
- To investigate the presence and distribution of poly(ADP-ribose) polymerase within rat testis chromatin.
- To analyze the size and protein association of ADP-ribose polymers in different nuclear fractions.
Main Methods:
- Enzymatic assays
- Activity blots
- Western blots
- Incubation of isolated nuclei with radiolabeled NAD+ ([14C]- or [32P])
- Autoradiographic analysis of nuclear protein extracts
Main Results:
- Poly(ADP-ribose) polymerase was detected in stripped chromatin loops and nuclear matrix of rat testis.
- Short ADP-ribose oligomers (≤3 residues) were associated with tightly bound chromosomal proteins (resistant to 2 M NaCl extraction).
- Longer ADP-ribose oligomers (8-13 residues) were associated with loosely bound chromosomal proteins.
- Histone-like proteins, tightly bound in chromatin loops and nuclear matrix, were identified as ADP-ribosylated.
Conclusions:
- Poly(ADP-ribose) polymerase is present in distinct nuclear compartments of rat testis.
- The size of ADP-ribose polymers correlates with the binding affinity of associated chromosomal proteins.
- Histone-like proteins are key targets of ADP-ribosylation within the nuclear matrix and chromatin loops.