InterPro domain: IPR011082

The CD1 family of proteins includes exosome-associated cofactor Rrp47, and DNA double-strand repair protein C1D. Both of these proteins are implicated in DNA double-strand repair and in nuclear exosome activity.

Rrp47 functions in nuclear RNA processing. Rrp47 is associated with nuclear exosomes, and with the nuclear exosome-specific 3'-5' exonuclease Rrp6.Rrp47 appears to be a substrate-specific nuclear cofactor that is required for the 3' processing of pre-rRNAs, snoRNAs and snRNAs (specifically U4 and U5) [ 1 ]. However, Rrp47 is not required for cytoplasmic exosome mRNA degradation. It also appears to have a role in DNA strand repair.

C1D is an inducible nuclear matrix proteins that interacts with and activates the DNA-dependent protein kinase essential for DNA double-strand repair and V(D)J recombination [ 2 ]. C1D can interact with condensin, which is required for DNA repair and replication checkpoint control [ 3 ]. C1D also binds to nuclear exosomes and might regulate their functional activities, as it has RNA-binding activity [ 4 ].

1. Rrp47p is an exosome-associated protein required for the 3' processing of stable RNAs. Mol. Cell. Biol. 23, 6982-92
2. Saccharomyces cerevisiae C1D is implicated in both non-homologous DNA end joining and homologous recombination. Mol. Microbiol. 46, 947-57
3. Cti1/C1D interacts with condensin SMC hinge and supports the DNA repair function of condensin. Proc. Natl. Acad. Sci. U.S.A. 101, 8078-83
4. C1D and hMtr4p associate with the human exosome subunit PM/Scl-100 and are involved in pre-rRNA processing. Nucleic Acids Res. 35, 2564-72