ASDURF (L0R819) review notes

2026-10-03 — initial review (MICROPROTEINS Tier 2)

Identity. ASDURF ("ASNSD1 upstream open reading frame protein", HGNC:53619) is a
96-aa peptide encoded by an upstream ORF in the 5' leader of the ASNSD1 mRNA. It is a
separate UniProt entry (L0R819) with its own HGNC symbol, so it has its own folder.
UniProt lists the host ASNSD1 protein (Q9NWL6) as the "external" alternative product.

Literature found (PubMed E-utilities, 2026-10-03). Query
ASDURF OR "ASNSD1 uORF" OR (ASNSD1 AND (uORF OR upstream open reading frame)) returned 6
hits; the relevant ones are PMID:23160002, PMID:31738558, PMID:38176414 (+ bioRxiv
preprint PMID:37205492 of the same work) and the Mol Cell preview PMID:38242097. A
PAQosome query (18 hits) found no further ASDURF-specific primary work.

Discovery / localization — PMID:23160002 (Slavoff et al. 2013, full text)

• Detected by peptidomics in K562 as "ASNSD1-SEP"; quantified by isotope dilution
  PMID:23160002.
• FLAG-tagged construct with native UTRs gives cytoplasmic signal in HEK293T
  PMID:23160002.
  Overexpression with tag; fine for a broad CC term.

PAQosome subunit — PMID:31738558 (Cloutier et al. 2020, J Proteome Res; abstract only)

• PMID:31738558
• PMID:31738558
• PMID:31738558
• Basis of ComplexPortal CPX-6145 (paqosome_human) annotations. Full text not cached;
  defer to ComplexPortal curators.

Medulloblastoma dependency — PMID:38176414 (Hofman et al. 2024 Mol Cell, full text)

• CRISPR screens of non-canonical ORFs; ASNSD1-uORF KO reduces viability of MYC-driven
  medulloblastoma lines, rescued by WT but not start-site-mutant cDNA.
• Co-IP/MS with prefoldin subunits, endogenous co-IP with PFDN6, GST pulldown
  PMID:38176414.
• DepMap/PRISM co-dependency clusters it with PFDL not canonical PFD
  PMID:38176414.
• KO of ASNSD1-uORF or PFDN2 gives an overlapping post-transcriptional proteome change
  (cell-cycle proteins), with little RNA change. Actin/tubulin unaffected.
• Interpretation: independent confirmation of PFDL/PAQosome membership. Cancer cell
  survival is a context-specific dependency, not a GO BP to assert.

Caller's context check

• Chen et al. 2020 Science (PMID:32139545, cached full text) does not mention ASNSD1 or
  ASDURF in its cached text; it did not report the PAQosome association. The PAQosome
  finding is Cloutier et al. 2020 (Coulombe lab), and the CRISPR-screen context is Hofman
  et al. 2024 (Prensner lab). Not cited in the review.

GOA decisions

• No MF: chaperone activity of the prefoldin-like module has not been shown for ASDURF
  itself; GO:0051082 is obsolete. Bare protein binding not used.
• No NEW terms. Prefoldin complex GO:0016272 not proposed — Hofman's data argue PFDL, not PFD.