Polymerase DNA Directed Theta (POLq)

The human genome contains multiple DNA polymerase genes. By searching sequence databases with the translated sequences of the human POLG and Drosophila mus308 DNA polymerase genes, Sharief et al. (1999) identified the novel human DNA polymerase theta (POLQ). They isolated human fetal spleen and human T-cell cDNAs representing the complete POLQ coding sequence. The predicted 1,762-amino acid POLQ protein contains an N-terminal ATP-binding domain and C-terminal DNA polymerase motifs A, B, and C, which classify POLQ as a family A-type DNA polymerase. The C-terminal regions of POLQ and the Drosophila mus308 gene product share 40% sequence identity; their N-terminal regions have no significant similarity.