DNA polymerase mu (Pol mu), homologous to TdT, could act as a DNA mutator in eukaryotic cells.


A novel DNA polymerase has been identified in human cells. Human DNA polymerase mu (Pol mu), consisting of 494 amino acids, has 41% identity to terminal deoxynucleotidyltransferase (TdT). Human Pol mu, overproduced in Escherichia coli in a soluble form and purified to homogeneity, displays intrinsic terminal deoxynucleotidyltransferase activity and a strong preference for activating Mn(2+) ions. Interestingly, unlike TdT, the catalytic efficiency of polymerization carried out by Pol mu was enhanced by the presence of a template strand. Using activating Mg(2+) ions, template-enhanced polymerization was also template-directed, leading to the preferred insertion of complementary nucleotides, although with low discrimination values. In the presence of Mn(2+) ions, template-enhanced polymerization produced a random insertion of nucleotides. Northern-blotting and in situ analysis showed a preferential expression of Pol mu mRNA in peripheral lymphoid tissues. Moreover, a large proportion of the human expressed sequence tags corresponding to Pol mu, present in the databases, derived from germinal center B cells. Therefore, Pol mu is a good candidate to be the mutator polymerase responsible for somatic hyper- mutation of immunoglobulin genes.



Historical Protein Properties (MW, pI, ...), Exonuclease Activity, Terminal Transferase, Source / Purification, Nucleotide Incorporation, Fidelity, Structure and Structure/Function, Alignments


new topics/pols set partial results complete validated


Polymerase Reference Property Result Context
Human Pol mu Domínguez O2000 Terminal Transferase Yes
Human Pol mu Domínguez O2000 Molecular Weight 5.5E+04 Dalton Technique: SDS-PAGE
Human Pol mu Domínguez O2000 3-5' Exonuclease (proofreading) No
Human Pol mu Domínguez O2000 Cloned or native Cloned in E. coli
Human Pol mu Domínguez O2000 Full length or truncated Full length

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