Immunocytochemical localization of chick DNA polymerases ? and ?+

Abstract

An immunofluorescent method using specific antibodies was employed to detect DNA polymerases α and β in chick cells. With monoclonal antibodies produced by four independent hybridoma clones, most of the DNA polymerase α was shown to be present in nuclei of cultured chick embryonic cells. With a polyclonal, but highly specific, antibody against DNA polymerase β, this enzyme was also shown to be present in nuclei. DNA polymerase α was detected in proliferating cells before cell contact and in lesser amount in resting cells after cell contact, indicating that its content is closely correlated with cell proliferation. On the other hand, similar amounts of DNA polymerase β were detected in proliferating and resting cells. Furthermore, DNA polymerase β was detected in nuclei of most cells, while DNA polymerase α was detected only in large round nuclei in seminiferous tubules of chick testis. DNA polymerase α is presumably present in cells that are capable of DNA replication, and during the cell cycle it seems to remain in the nuclei during the G₁, S, and G₂ phases, but to leave from condensed chromatin for the cytoplasm during the mitotic phase.