I counted both the yeast and mammalian names in the following table as correct:
| Yeast gene name | Mammalian gene name | Protein & function |
| ? | XRCC4 | Unknown function |
| HDF2 | XRCC5 | Ku80 (part of DNA protein kinase) |
| HDF1 | XRCC6 | Ku70 (part of DNA protein kinase) |
| ? | XRCC7 | Catalytic subunit of DNA protein kinase |
| RAD50 | RAD50 | Stimulates Mre11 exonuclease |
| MRE11 | MRE11 | 3' to 5' exonuclease |
| XRS2 | NBS1 | Interacts with Rad50, Mre11 |
In addition, I gave extra credit (but not beyond the maximum score of 8 points for this question) if you mentioned DNaseIV/FEN-1 and/or DNA ligase, both of which may be involved in the final stages of NHEJ, although there is not yet any genetic evidence for their involvement.
Note that, at this point, the roles of KU and of the DNA protein kinase in NHEJ are not clear. From genetic evidence we know they are required, but we don't know exactly what they do. A possible role for the Mre11 exonuclease seems more clear from the recent studies in the Gellert laboratory, but that role is still not proved.
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