Ku80 (IPR024193)

Short name: Ku80

Overlapping homologous superfamilies

Family relationships



This group consists of eukaryotic proteins containing the Ku80 domain. In eukaryotes it has been shown that Ku protein is involved in repairing DNA double-strand breaks by non-homologous end-joining [PMID: 11839498, PMID: 10377944, PMID: 14697755]. Ku is a heterodimer of approximately 70 kDa and 80 kDa subunits [PMID: 11493912]. Both these subunits have strong sequence similarity and it has been suggested that they may have evolved by gene duplication from a homodimeric ancestor in eukaryotes [PMID: 11839498]. The prokaryotic Ku members are homodimers and they have been predicted to be involved in the DNA repair system, which is mechanistically similar to the eukaryotic non-homologous end joining [PMID: 11483577, PMID: 11445083]. Recent findings have implicated yeast Ku in telomeric structure maintenance in addition to non-homologous end-joining [PMID: 11029034]. Some of the phenotypes of Ku-knockout mice may indicate a similar role for Ku at mammalian telomeres [PMID: 11516951].

Evolutionary notes: With the currently available phyletic information it is difficult to determine the correct evolutionary trajectory of the Ku domain. It is possible that the core Ku domain was present in bacteria and archaea even before the presence of the eukaryotes. Eukaryotes might have vertically inherited the Ku-core protein from a common ancestor shared with a certain archaeal lineage or through horizontal transfer from bacteria. Alternatively, the core Ku domain could have evolved in the eukaryotic lineage and then horizontally transferred to the prokaryotes. Sequencing of additional archaeal genomes and those of early-branching eukaryotes may help resolve the evolutionary history of the Ku domain.

Structure notes: The eukaryotic Ku heterodimer is comprised of an alpha/beta N-terminal domain, a central beta-barrel domain and a helical C-terminal arm [PMID: 11493912]. Structural analysis of the Ku70/80 heterodimer bound to DNA indicates that subunit contacts lead to the formation of a highly charged channel through which the DNA passes without making any contacts with the DNA bases [PMID: 11493912].

For additional information please see [PMID: 9477961].

GO terms

Biological Process

GO:0006310 DNA recombination
GO:0006303 double-strand break repair via nonhomologous end joining
GO:0000723 telomere maintenance

Molecular Function

GO:0003677 DNA binding
GO:0003684 damaged DNA binding
GO:0042162 telomeric DNA binding

Cellular Component

GO:0043564 Ku70:Ku80 complex
GO:0005634 nucleus

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.