Tight association of DNA polymerase alpha with granular structures in the nuclear matrix of chick embryo cell: immunocytochemical detection with monoclonal antibody against DNA polymerase alpha.

Immunofluorescent methods using a monoclonal antibody against chick DNA polymerase alpha and a rabbit antibody against chick DNA polymerase beta demonstrated that both DNA polymerases alpha and beta are present mainly in nuclei of cultured chick embryo cells. Fluorescence produced by anti-DNA polymerase alpha was more intense in the small granules than in other parts of the nucleus but, fluorescence produced by anti-DNA polymerase beta was distributed evenly in the nucleus. Cells first were treated with Nonidet P-40, followed by treatment with 50 micrograms/ml pancreatic DNase and 2 M NaCl in order to prepare the nuclear matrix. Fluorescence produced by anti-DNA polymerase alpha was still detectable in the granules after these treatments, but most of the fluorescence produced by anti-DNA polymerase beta disappeared. Our results indicate that a part of DNA polymerase alpha is tightly bound to a special structure present in the nuclear matrix which presumably is the DNA replication machinery.