The intracellular localizing of mammalian DNA ligase I

DNA replication is cruciaI for the transmission of genetic information. Understanding the enzymology involved in this complex process will allow further insight into its mechanism. Experimental evidence indicates a role for DNA ligase I in DNA replication. Techniques of molecular and cellular biology and immunology were utilized in this study to further investigate DNA ligase I and clarify its involvement and interaction with other proteins in DNA replication. Immunofluorescence studies were performed to examine the intracellular distribution of DNA ligase I. Confocal analysis of indirect immunofluorescence detection of DNA ligase I using affinity purified anti-human DNA ligase I antibodies showed nuclear localization of DNA ligase I in distinct foci resembling those structures seen in detection of centres of DNA replication and other DNA replication proteins. Immunoprecipitation experiments were performed on extracts of MDBK cells to examine possible interactions of DNA ligase I with the DNA replication cofactor, PCNA; and no interactions were detected.