FIG. 1.

The human DNA ligase III cDNA contains a putative mitochondrial targeting sequence. (A) Deduced amino acid sequence of the human DNA ligase III cDNA upstream sequence from the first in-frame ATG (M₁) to the second ATG (M₂). M2 has previously been designated the translation initiation site for the nuclear ligase III protein (3, 47). The underlined sequence represents the alpha-helical region as predicted by the program pHDsec (27, 28). Plus signs overlie positively charged residues; the amino acids in bold comprise the putative cleavage recognition sequence, and the arrow indicates the putative cleavage site. (B) Amino acid residues 1 through 35 (underlined in panel A) were plotted as specified by Schiffer and Edmundson (30). Positively charged residues are indicated.