ATP-Dependent DNA Ligase Coupled to a KU-domain Protein

Look at the coupling between the ATP-dependent DNA ligase and the Ku domain protein. Here is what NCBI has to say about the KU domain proteins:

Notes on KU domains from NCBI: Ku-core domain, Ku-like subfamily; composed of prokaryotic homologs of the eukaryotic DNA binding protein Ku. The alignment includes the core domain shared by the prokaryotic YkoV-like proteins and the eukaryotic Ku70 and Ku80. The prokaryotic Ku homologs are predicted to form homodimers. It is proposed that the Ku homologs are functionally associated with ATP-dependent DNA ligase and the eukaryotic-type primase, probably as components of a double-strand break repair system.

Note the weirdness going on with the ATP-dependent DNA ligase (the red genes labeled as "1"). Some are much longer than others suggesting the presence of extra domains in some of them.