Proliferating cell nuclear antigen/cyclin in the ciliate Euplotes eurystomus: localization in the replication band and in micronuclei.
Human autoimmune sera specific for proliferating cell nuclear antigen (PCNA)/cyclin (auxiliary protein for DNA polymerase delta) demonstrated the presence of epitopes within the macro- and micronuclei of the hypotrichous ciliated protozoa Euplotes eurystomus. Tightly bound PCNA/cyclin was localized at the site of DNA synthesis in macronuclei, the rear zone of the replication band. Starvation or heat shock, conditions that reduce macronuclear replication, resulted in a decrease of PCNA/cyclin in replication bands. Micronuclei also exhibited PCNA/cyclin localization which persisted for a large proportion of the vegetative cell cycle and exhibited significant resistance to adverse culture conditions. Immunoprecipitation of 35S-labeled soluble Euplotes proteins with PCNA/cyclin autoimmune sera revealed a spectrum of low molecular mass proteins. PCNA/cyclin-like proteins have now been observed in the widely divergent species: human, rat, amphibian, yeast, and ciliated protozoa.
Olins
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University of Tennessee-Oak Ridge, Graduate School of Biomedical Sciences 37831.
Olins
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Cacheiro
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Tan
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D000818:Animals; D001324:Autoantigens / Q000276:immunology; D002467:Cell Nucleus / Q000648:ultrastructure; D016798:Ciliophora / Q000166:cytology* / Q000648:ultrastructure; D000939:Epitopes / Q000032:analysis; D005455:Fluorescent Antibody Technique; D006358:Hot Temperature; D006801:Humans; D048631:Micronucleus, Germline / Q000648:ultrastructure*; D008854:Microscopy, Electron; D009687:Nuclear Proteins / Q000032:analysis* / Q000096:biosynthesis / Q000302:isolation & purification; D018809:Proliferating Cell Nuclear Antigen
D001324:Autoantigens; D000939:Epitopes; D009687:Nuclear Proteins; D018809:Proliferating Cell Nuclear Antigen