Human DNA Polymerase III (R-DNA Polymerase): Distinction from DNA Polymerase I and Reverse Transcriptase

Abstract

DNA polymerase III is an enzyme activity in eukaryotic cells which under certain conditions shows strong preference for polyadenylic acid as template when primed by oligodeoxythymidylate. Its first complete separation from other DNA polymerases in human lymphoblasts is reported. This enzyme is biochemically and immunologically distinct from DNA polymerase I and from viral reverse transcriptase from a primtate type C virus.

DNA polymerase activity of cultured rheumatoid synovial cells

“…Poly (rA):oligo (dT)lZ-lS contains an RNA template which is copied by both oncornavirus and normal cellular DNA polymerases, and hence is a nonspecific measure of RNA-directed DNA polymerase activity (RDDP). Poly (rC):oligo (dG)12-18 contains an RNA template which has been shown to be highly specific for the oncornavirus RDDP (6,8,12).…”

“…Enzyme activity w i t h these synthetic templates is several fold greater t h a n w i t h n a t u r a l nucleic acid heteropolymers, allowing assay of small q u a n t i t i e s of enzyme. In addition, t h e preferential utilization of p a r t i c u l a r synthetic templates by individual polymerases provides a means of characterization of these enzymes (6,8,12).…”

“…Oncornaviruses (oncogenic RNA viruses) contain an RNAdirected DNA polymerase (RDDP), sometimes referred to as "reverse transcriptase." The oncornavirus RDDP is a unique enzyme with antigenic specificity and substrate preferences that enable it to be distinguished in cell extracts from normal host nucleic acid polymerases (6). Assay for this enzyme is a highly sensitive means of detecting the virus and has been used to follow the induction of C-type virus from mouse cells (7) and to search for oncornavirus infection in human cancers and lymphoproliferative disorders (8-10).…”

DNA polymerases of eukaryotes

“…It has been less well studied than DNA polymerases-a or -0 and its purification will no doubt prove a difficult undertaking because of the low levels. It has been found in HeLa cells [82], human lymphoblastoid cells [83], calf thymus [70,84] and mouse myeloma [56]. Although its level is doubled within two hours of the start of S phase in HeLa cells, it is not known what role if any it plays in replication.…”

Studies on a DNA polymeraseγ‐like enzyme from wheat embryos

“…DNA polymerase 3' is the latest found in animal cells. It was first described in HeLa cells [2] and recently found in other organisms [3][4][5][6][7]. Its main property is to recognize poly rA-dTl 2 at a much higher rate than a deoxyribonucleic acid template like poly dA-dT~ 2.…”