Figure 5. Multiple alignment of the N-terminal regions in mammalian Pol.

ι homologues. In the upper amino acid sequence alignments, the Met residues of human and mouse Pol ι that were previously assigned as the first residue are underlined. In the lower sequences, the regions from the newly assigned Met start codon to the previously assigned one in the gene coding for the 740 or 739 aa protein are shown for human Pol ι, and are derived from the NCBI entries NM_007195 and AK301578, respectively. Many cDNA clones with the 5′-end sequence identical to either one of the two entries are found in human EST libraries at almost equal frequencies, implying that the difference is due to heterogeneity, not to sequence error. CGA repeats in the newly identified N-terminal sequences are denoted by a horizontal line with an arrow.