CLONING AND SEQUENCE-ANALYSIS OF A CDNA CODING FOR THE MURINE DNA-LIGASE-I ENZYME

A complementary DNA (2961 bp) containing the complete coding sequence for murine DNA ligase I was isolated from a mouse fibroblast cDNA libr ary using a cDNA encoding the human protein as a probe. An open readin g frame of 2748 bp, encoding a protein of 916 amino acids (aa), was id entified. Northern blot analysis of total RNA extracted from mouse fib roblasts showed a single band with a mobility corresponding to a size of 3.2 kb whose level increases upon serum stimulation of quiescent mo use NIH-3T3 cells. Alignment of the murine and human deduced aa sequen ces showed an overall 83% identity, that rises to 91% if only the sequ ence on the C-terminal portion of the protein containing the active si te is considered.