KCTD10 (Q9H3F6) — curation notes

KCTD10 (potassium channel tetramerization domain-containing 10; also BACURD3)
is, despite the "potassium channel tetramerization domain" name, not an ion
channel. It is the substrate-recognition subunit of a Cullin-3–RBX1 (CRL3 /
BCR) RING E3 ubiquitin ligase. Family: BACURD (BTB/POZ adapters for CUL3).

Core molecular function

• Substrate-specific adapter of a BCR(BTB-CUL3-RBX1) E3 ubiquitin ligase
  complex; mediates ubiquitination of multiple substrates for proteasomal or
  lysosomal degradation, or non-degradative (signaling) ubiquitination
  [UniProtKB:Q9H3F6 FUNCTION].
• Binds CUL3 directly via its N-terminal BTB/POZ domain and oligomerizes —
  forms a homopentamer and a 5:5 heterodecamer with CUL3 PMID:28963344.
• GO MF: ubiquitin-like ligase-substrate adaptor activity (GO:1990756, IDA
  PMID:30404837); complex: Cul3-RING ubiquitin ligase complex (GO:0031463).

Substrate-specific outcomes (pleiotropic; non-core)

• RHOB — K63-linked polyubiquitination → lysosomal degradation, preserving
  endothelial barrier function. [PMID:29358211 "RhoB is primarily K63
  polyubiquitinated and subsequently degraded in lysosomes."; "Cullin-3–Rbx1–
  KCTD10–mediated RhoB ubiquitination and degradation preserves endothelial
  barrier function"]
• CEP97 — proteasomal degradation upon serum starvation, removing the
  CEP97–CP110 complex from the mother centriole to license primary cilium
  formation. PMID:30404837
• SLC7A11 (xCT) — destabilization by polyubiquitination → reduced cystine
  uptake and GSH synthesis → positive regulation of ferroptosis. The
  CRL3^KCTD10 E3 is opposed by the deubiquitinase USP18. PMID:38959043
• TICAM1/TRIF — K27-linked polyubiquitination at Lys-523, promoting
  TLR3/4-mediated innate immune signaling [UniProtKB FUNCTION, PMID:31511519].
• KCTD13 — degradative ubiquitination controlling neuronal progenitor
  proliferation (by similarity); TCEA2 — ubiquitination to resolve
  transcription–replication conflicts [UniProtKB FUNCTION, PMID:41062692].

Localization, structure, isoforms

• Subcellular: nucleus PMID:19125419 and cytoplasm (IDA
  PMID:30404837); nucleoplasm by HPA immunofluorescence (GO_REF:0000052).
• Homo-oligomer (BTB-mediated); interacts with CUL3, KCTD13, TNFAIP1, PCNA,
  POLD2. Three splice isoforms (Q9H3F6-1/-2/-3).

Curation flag — confirmed mis-citation propagated into GOA

The GOA annotation GO:0160020 positive regulation of ferroptosis (IDA,
PMID:30404837) cites the CEP97/ciliogenesis paper, which contains no
ferroptosis/SLC7A11 content (verified abstract). The correct primary source is
PMID:38959043 (Gou et al., PNAS 2024), which UniProt cites for this exact
function. This is the same mechanically-valid-but-semantically-wrong citation
found in GO-CAM gomodel:69729a3800005900 (USP18/SLC7A11 activity), where
PMID:30404837 was inherited from the (correctly-cited) KCTD10 adaptor activity
onto the antagonist node. The ferroptosis biology is correct; only the
reference is wrong. Recorded in the GO:0160020 review with additional_reference_ids.

Summary

KCTD10's single core molecular function — CRL3 substrate-recognition adapter —
is deployed against several unrelated substrates (RHOB, CEP97, SLC7A11, TICAM1,
KCTD13, TCEA2), so its many biological-process annotations (Rho signaling,
ciliogenesis, ferroptosis, endothelial barrier, innate immunity) are
substrate-specific consequences of one ubiquitin-ligase-adapter activity rather
than independent core functions.