Abstract

In a number of different eucaryotic cells, interphase chromatin contains poly(ADP-ribose) polymerase [l-3 J. It incorporates the ADP-ribose moiety of NAD into poly(ADP-ribose) of varying chainlength (l-40 residues). The polymer is covalently bound to histones and non&stone proteins. The polymerase has been found also in the cytoplasm of HeLa cells tightly bound to ribosomes [4]. This enzyme has also been detected in mitotic cells [5] but its location in isolated metaphase chromosomes not yet examined. Since the occurrence of this enzyme in chromatin from interphase cells does not necessarily mean that it is present in an enzymaticaIly active form in metaphase chromosomes, it was considered important to establish this. We show that metaphase chromosomes from HeLa S3 cells contain the enzyme in an active form. The enzyme seems to be an integral part of metaphase chromosomes and not merely a contamination of enzyme present in the cytoplasm [4], since metaphase chromosomes isolated by different methods yielded about the same result. Finally when isolated metaphase chromosomes were incubated in vitro with [14C]NAD, the chromosomes became ADP-ribosylated and hence could serve as an acceptor for ADP-ribosylation. This might suggest that ADPribosylation of metaphase chromosomes plays a role during mitosis.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.