mitfb notes (Danio rerio, UniProt F1Q885, ZFIN:ZDB-GENE-010919-1)

2026-09-27 — review for DANRE_DUPLICATION (pair mitfa/mitfb)

Deep research status

• Automated deep research FAILED for mitfb: the Edison/Falcon provider returned
  402 Payment Required and the OpenAI key was invalid. Per project instructions it was
  not retried. No mitfb-deep-research-*.md file exists; the literature research below
  was done manually from cached publications (Europe PMC search for
  (mitfb OR "mitf-b") AND (zebrafish OR fish OR teleost), 102 hits, screened by title).

Papers fetched for this review

• PMID:23139843 Lane & Lister 2012 (full text) — mitfb nonsense alleles, mitfa;mitfb double
  mutants, RPE.
• PMID:37823232 Miyadai et al. 2023 (full text) — medaka and zebrafish mitfa;mitfb double
  mutants.
• PMID:40123122 Korzeniwsky et al. 2025 (full text) — zebrafish mitfb PTC allele in mitfa
  background; xanthophores.
• PMID:42663426 Lister et al. 2026 (abstract only) — mitfa/mitfb/tfec triple mutants, RPE.
• PMID:20333216 Braasch et al. 2009 (full text) — FSGD pigmentation genes, synteny table.
• PMID:23781143, PMID:24118994 (medaka mitf1/mitf2), PMID:35691494 (tilapia) — lineage context.
  Note: the medaka gene names used by Li et al. (mitf1/mitf2) are not mapped onto
  zebrafish mitfa/mitfb in the abstracts; do not assume mitf2 = mitfb.

Findings with provenance

• Discovery and expression: PMID:11543618; PMID:11543618.
• Protein-level capacity: PMID:11543618.
• Isoform correspondence: PMID:11543618; PMID:12019239
• Loss of function: two ENU nonsense alleles, hu3857 (exon 2) and hu3561 (exon 7, bHLH-LZ):
  PMID:23139843;
  double mutants with mitfa: PMID:23139843.
• Xanthophores: PMID:37823232; independently
  PMID:40123122
• Lineage-specific resolution: in medaka PMID:37823232; and
  PMID:40123122.
• RPE redundancy with tfec (abstract only): PMID:42663426.

Curation decisions (summary)

• MF (IBA + IDA GO:0000981; IBA GO:0000978): ACCEPT — protein retains melanogenic TF activity.
• Melanocyte differentiation (IBA, IGI PMID:11543618): KEEP_AS_NON_CORE — the IGI is a
  cross-rescue that shows protein capacity when driven by the mitfa promoter; endogenous
  zebrafish mitfb is not expressed in NC melanoblasts and mitfb nulls have normal
  melanophores.
• DNA-templated transcription (IDA): MODIFY -> GO:0006357 (TF regulates, does not execute,
  transcription); consistent with mitfa.
• NEW GO:0050936 xanthophore differentiation, supported by two independent double-mutant
  studies (PMID:37823232, PMID:40123122); mirrored on mitfa.
• Not proposed as NEW: RPE/eye pigmentation (only triple mutant with tfec, abstract-only);
  epiphysis / olfactory bulb roles (expression only, no function tested).