Rad9-Hus1-Rad1 (9-1-1) checkpoint clamp in Drosophila melanogaster

The 9-1-1 complex is a heterotrimeric ring of Rad9, Hus1 and Rad1 that is structurally related to the PCNA sliding clamp. An RFC-like clamp loader places it at 5' recessed junctions of single-stranded DNA gaps and resected ends, where it helps recruit and activate the ATR kinase in the DNA damage and replication checkpoint. In Drosophila, the Hus1 ortholog is named Hus1-like.

The clamp loader (Rad17-RFC in other species) is outside the module. Each subunit is modelled as a part because the trimer has no further sub-structure. No molecular function is assigned. The 9-1-1 trimer is a DNA clamp that is loaded at damage sites and scaffolds checkpoint signalling; the GO term for DNA clamp activity (GO:0061777) is obsolete, and the 3'-5' exonuclease activity inferred for Rad9 (ISS) is not established for the fly protein. FlyBase groups realized by this module: CCC-911 (FBgg0002116). Participants were generated from the FlyBase gene-group membership and mapped to UniProtKB by projects/FLYBASE_GENE_GROUPS/generate_modules.py from module_specs/dmel_9_1_1_checkpoint_clamp.yaml. Member genes with a gene review in this repository: Hus1-like, Rad1, Rad9.