Ubiquitin-binding protein which acts as an adapter for ATPase cdc-48.1 and/or cdc-48.2, conferring substrate specificity (PubMed:20977550, PubMed:26842564, PubMed:28368371). Together with ubxn-1 and ubxn-2, plays a role in hermaphrodite spermatogenesis probably by promoting the degradation of sex determination terminal factor tra-1 (PubMed:20977550). During mitosis, ensures the degradation of DNA licensing factor cdt-1 and the disassembly of the DNA replication CMG helicase complex by promoting the dissociation from chromatin of several of its components including cdc-45 and sld-5 (PubMed:26842564, PubMed:28368371). Forms a complex composed of ubxn-3, cdc-48.1, ufd-1 and npl-4.1 (PubMed:20977550). Forms a complex composed of ubxn-3, cdc-48.1 and/or cdc-48.2 and substrate cdt-1 (PubMed:26842564). Interacts (via FPK motif) with cdc-48.1 (via N-terminus) and cdc-48.2 (via N-terminus) (PubMed:20977550, PubMed:26842564). Interacts (via N-terminus) with cdt-1 and ubiquitinated protein substrates; the interaction is cdc-48-independent (PubMed:26842564). May interact with npl-4.1 (PubMed:20977550). Colocalizes with cdc-48.1 to the perinuclear region in spermatocytes (PubMed:20977550). Localizes to the nucleus during S phase in a cdc-48 and npl-4-dependent manner (PubMed:26842564). Expressed in the germline (at protein level) (PubMed:17498661, PubMed:20977550). Expressed in spermatocytes but not in mature sperm (at protein level) (PubMed:20977550). Expressed in the spermatheca and nerve cells (PubMed:17498661). Expressed in embryos (at protein level) (PubMed:17498661, PubMed:26842564). Also expressed in L4 larvae and adults (PubMed:17498661). Expressed to a lesser extent between L1 and L3 larval stages (PubMed:17498661). Causes approximately 30 percent embryonic lethality (PubMed:26842564). RNAi-mediated knockdown does not cause any visible phenotype (PubMed:20977550). Cell division at the 3-cell stage is delayed. In a cdc-48.1 (tm544) mutant background, the delay in cell cycle progression is further enhanced and DNA replication is impaired resulting in the formation of DNA repair rad-51 foci (PubMed:26842564). In addition, cdt-1 degradation and disassembly of cdc-45 and sld-5 from the chromatin during mitosis is impaired (PubMed:26842564). Simultaneous RNAi-mediated knockdown of lrr-1, causes a failure to disassemble components of the CGM helicase complex psf-1, cdc-45 and spd-5 from the chromatin resulting in their abnormal association with chromatin during mitosis (PubMed:28368371). Simultaneous RNAi-mediated knockdown of ubxn-1 and ubxn-2, causes 50 percent embryonic lethality (PubMed:20977550). The surviving hermaphrodite progeny are sterile due to a lack of sperm (PubMed:20977550). Abnormal accumulation of sex determination terminal factor tra-1 (PubMed:20977550). Germline development is normal (PubMed:20977550). In males, sperm production is normal (PubMed:20977550).