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. By recruiting and promoting the degradation of ubiquitinated proteins, plays a role in the ubiquitin fusion degradation (UFD) pathway. Has a role in the endoplasmic reticulum-associated degradation (ERAD) pathway which mediates the cytoplasmic elimination of misfolded proteins exported from the ER. Involved in spindle disassembly. Component of the ribosome quality control complex (RQC), a ribosome-associated complex that mediates ubiquitination and extraction of incompletely synthesized nascent chains for proteasomal degradation. CDC48 may provide the mechanical force that dislodges the polyubiquitinated nascent peptides from the exit channel. Required for ribophagy, a process which relocalizes ribosomal particles into the vacuole for degradation in response to starvation. Has a role in substrate recognition mediating rbd2-dependent cleavage of sterol regulatory element-binding protein sre1 and sre2