ATP-dependent chaperone which probably uses the energy provided by ATP hydrolysis to generate mechanical force to unfold substrate proteins, disassemble protein complexes, and disaggregate protein aggregates (PubMed:18854144, PubMed:18782221, PubMed:22768338). Can also prevent aggregation of unfolded proteins also in an ATP-independent manner (PubMed:18782221). Targets polyubiquitinated proteins for proteasomal degradation by binding to 'Lys-48'-linked polyubiquitin chains (PubMed:19545544). Involved in the cytoplasmic elimination of misfolded proteins exported from the ER (PubMed:16647269, PubMed:17825049, PubMed:21317884, PubMed:22768338, PubMed:25652260). This pathway, known as ERAD, prevents the activation of the unfolded protein response (UPR) caused by the accumulation of misfolded proteins in the ER (PubMed:16647269, PubMed:17825049, PubMed:21317884, PubMed:22768338, PubMed:25652260). In association with helicase him-6 and GTPase crp-1, regulates the unfolded protein response (UPR) following ER stress, probably independently of the ERAD pathway (PubMed:18458060). Together with udf-2 and chn-1, regulates myosin assembly in body wall muscles by targeting myosin chaperone unc-45 for proteasomal degradation (PubMed:17369820). Together with the ufd-1-npl-4 complex, controls the switch from spermatogenesis to oogenesis by regulating E3 ligase cul-2 complex-mediated tra-1 proteasomal degradation (PubMed:19773360). During oocyte meiosis and together with cdc-48.2, required for chromosome condensation at the diakinesis phase in prophase I and for progression of metaphase I (PubMed:17512499). During the first embryonic cell division, regulates DNA replication and thus chromosome segregation and decondensation, and nuclear envelope re-assembly (PubMed:18097415, PubMed:18854144, PubMed:18728180, PubMed:21981920, PubMed:26842564, PubMed:28368371). In S phase and in association with ufd-1, npl-4.1 and/or npl-4.2 and ubxn-3, ensures the degradation of DNA licensing factor cdt-1 after the initiation of DNA replication and thus 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:21981920, PubMed:26842564, PubMed:28368371). Regulates ubxn-3 nuclear localization during S phase (PubMed:26842564). During the first embryonic cell divisions and together with cdc-48.2, regulates the re-assembly of the nuclear envelope after mitosis possibly by inactivating kinase air-2, a component of the chromosomal passenger complex (CPC) (PubMed:18097415). However, in another study, cdc-48.1 does not appear to be implicated in the regulation of air-2 (PubMed:18854144). ATP + H2O = ADP + H(+) + phosphate The first ATP-binding region has low ATPase activity (PubMed:21454554). The second ATP-binding region is responsible for ATPase activity (PubMed:21454554). ATP binding to the first ATP-binding region induces intrinsic activity of the second ATP-binding region (PubMed:21454554). While ATP binding to the first ATP-binding region appears to prevent ATP hydrolysis by the second ATP-binding region, ADP-binding to first region promotes the coordinate and cooperative ATPase cycle of the second ATP-binding region (PubMed:21454554). ATP binding to the first ATP-binding region induces a conformational change, promoting the rotation of the first ATP-binding region relative to the second ATP-binding region in the hexamer (PubMed:24055316). Inhibited by N-ethylmaleimide (NEM) (PubMed:18782221). Homohexamer; oligomerization is ATP-independent (PubMed:18782221, PubMed:24055316). Forms a ring-shaped particle of 18.3 nm diameter, that displays 6-fold radial symmetry (PubMed:24055316). Interacts with cdc-48.2 and thus may form heterohexamers (PubMed:16647269, PubMed:17369820, PubMed:25721663). Forms a complex composed of cdc-48.1, him-6 and crp-1; within the complex, interacts with helicase him-6 and GTPase crp-1 (PubMed:18458060). Forms a complex composed of deubiquitinating enzyme atx-3, adapter ubxn-5 and cdc-48.1; within the complex, interacts (via N-terminus) with ubxn-5 and with atx-3 (PubMed:19545544). Forms a complex composed of deubiquitinating enzyme atx-3, E4 ubiquitin-protein ligase ufd-2 and cdc-48.1; within the complex, interacts with atx-3 and (via DDDLYN motif) with ufd-2 (PubMed:21317884, PubMed:27669035). Interacts (via N-terminus) with atx-3 (via RRDR motif); the interaction is not required for atx-3 enzymatic activity (PubMed:19545544, PubMed:21317884). Forms a complex composed of cdc-48.1, myosin chaperone unc-45, ubiquitin-protein ligases ufd-2 and chn-1; within the complex, interacts (via DDDLYN motif) with ufd-2 and targets myosin chaperone unc-45 for proteasomal degradation (PubMed:17369820, PubMed:27669035). Forms a complex composed of ubxn-3, ufd-1, npl-4.1 and cdc-48.1; within the complex, interacts (via N-terminus) with ubxn-3 (via FPK motif) and with ufd-1 (PubMed:16647269, 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 N-terminus) with ubxn-1 (PubMed:16647269, PubMed:20977550). Interacts (via N-terminus) with ubxn-2 (PubMed:23649807, PubMed:20977550). Interacts (via N-terminus) with ubxn-4 (PubMed:20977550). Interacts with ubxn-6 (PubMed:20977550). Interacts with ufd-3 (PubMed:25721663). Does not interact with air-2 (PubMed:18854144). Colocalizes with ubxn-1, ubxn-2 and ubxn-3 to the perinuclear region in spermatocytes (PubMed:20977550). Localizes to the perinuclear region in intestinal cells (PubMed:25721663). Expressed in germ cells and spermatheca (PubMed:16701565). Expressed in body wall muscles (PubMed:17369820). Expressed highly in embryos (at protein level) (PubMed:16701565, PubMed:17369820). Expression decreases in larvae and increases again in adults (at protein level) (PubMed:16701565, PubMed:17369820). At the L4 larval stage, expressed in the proximal gonad, predominantly at the pachytene stage and in spermatocytes (PubMed:19773360). Not expressed in sperm (PubMed:19773360). Induced upon ER stress. Repressed by starvation and oxidative stress. RNAi-mediated knockdown causes partial embryonic lethality (PubMed:15716356, PubMed:18854144). Impairs response to ER stress (PubMed:18458060). Abnormal accumulation of myosin chaperone unc-45 in body wall muscles (PubMed:17369820). RNAi-mediated knockdown in an unc-45 (m94) mutant background, restores motility (PubMed:17369820). Simultaneous RNAi-mediated knockdown of cdc-48.2 in embryos causes embryonic lethality (PubMed:15716356, PubMed:16647269, PubMed:18097415, PubMed:18854144, PubMed:18728180). Defects in oocyte meiosis I progression (PubMed:17512499). Defects in embryo S phase DNA replication causing delays in cell cycle progression (PubMed:17512499, PubMed:18728180, PubMed:21981920, PubMed:26842564, PubMed:28368371). At the end of mitosis, impairs chromatin decondensation and nuclear envelope re-assembly (PubMed:18728180, PubMed:18854144, PubMed:18097415). In addition, abnormal accumulation of air-2 on mitotic chromatin and impaired air-2 activation (PubMed:18097415). Does not affect ER transition into sheet-like structures at the onset of embryonic mitosis (PubMed:15716356). Simultaneous RNAi-mediated knockdown of cdc-48.2 in young adults decreases lifespan, induces the unfolded protein response, increases overall levels of polyubiquitinated proteins, and impairs the degradation of misfolded ER proteins (PubMed:16647269, PubMed:17825049, PubMed:17369820, PubMed:21317884, PubMed:22768338). Causes defects in germline development (PubMed:20977550). In an atx-3 (gk193) mutant background, causes a 50 percent increase in longevity, a delay in age-related muscle degeneration and resistance to oxidative and heat stresses (PubMed:21317884). Belongs to the AAA ATPase family. CDC48 subfamily. The role of cdc-48.1 in the regulation of kinase air-2, a component of the chromosomal passenger complex (CPC), is controversial. One study suggests that cdc-48.1 inactivates air-2 at the end of mitosis whereas a second study shows that cdc-48.1 is not implicated in the regulation of air-2.