Reference protein: P40818. This is a manual literature synthesis using fetched primary-publication text and the reviewed human UniProt record.
The original human UBPY study measured cleavage of linear and isopeptide-linked ubiquitin chains with recombinant protein and immunoprecipitated cellular material. Changes in protein abundance/activity affected cellular ubiquitination patterns and fibroblast cell-cycle entry. The defining molecular function is cysteine-type deubiquitinase activity. PMID:9628861(https://pubmed.ncbi.nlm.nih.gov/9628861/)
The biochemical reaction removes ubiquitin, but removal can be a step in sorting and degradation pathways. A protein may participate in ubiquitin-dependent protein catabolism without directly cleaving the cargo polypeptide. USP8 substrate-specific effects on stability must be considered separately; deubiquitinase activity is not a universal instruction to mark all catabolic BP annotations incorrect. PMID:9628861(https://pubmed.ncbi.nlm.nih.gov/9628861/)
The reviewed human source links USP8 to endosomal ubiquitin dynamics, cargo sorting, ESCRT-0 stability and EGFR degradation. These are mechanistic leads for the horse comparison. The nearly complete and highly conserved selected horse sequence supports transfer of catalytic function, but does not experimentally validate each human substrate or disease association in horse. PMID:9628861(https://pubmed.ncbi.nlm.nih.gov/9628861/)
The source caches distinguish full text from abstract-only access; unresolved experimental annotations should remain UNDECIDED until their supporting material is available. This synthesis focuses on the biochemical mechanism, localization, and evidence needed for the paired horse prediction assessment; it does not certify every existing GO annotation.