Thiol protease which recognizes and hydrolyzes the peptide bond at the C-terminal Gly of ufm-1, a ubiquitin-like modifier protein bound to a number of target proteins. Required, with oct-4, for the localization of a subset of 7 transmembrane domain odorant receptors, including odr-10, to the cilia of olfactory neurons AWA and AWC. Operates in aggregation behavior, and responses to oxygen levels. Interacts with odr-4. Recruited to the endoplasmic reticulum upon interaction with odr-4. Belongs to the peptidase C78 family.