tmc2b notes (Danio rerio, transmembrane channel-like 2b; UniProt F1QZE9)

2026-09-28 — session log (DANRE_DUPLICATION batch 3, random TGD_tree sample)

Deep research: not available (Edison/Falcon 402 Payment Required; OpenAI key invalid). Not attempted, per
instructions; literature searched by hand via Europe PMC. Most shared pair literature and the pair analysis are
recorded in ../tmc2a/tmc2a-notes.md and ../tmc2a/tmc2a-bioinformatics/RESULTS.md.

Accession F1QZE9 (Swiss-Prot TMC2B_DANRE, 892 aa), ZFIN:ZDB-GENE-060526-262, Ensembl ENSDARG00000030311,
chr5:25.62 Mb, adjacent to tmc1: PMID:32371604

Expression

• Neuromasts: PMID:25114259
• Inner ear: peripheral/extrastriolar with tmc1 PMID:38035267
• Not regulated by prdm1a (ear/lateral-line fate switch): PMID:40825768
• Adult: ear only among adult tissues tested by RT-PCR PMID:25114259
• Bgee (my expression_compare.py) reports tmc2b in neuromast hair cells (in situ) plus low bulk RNA-seq calls in
  muscle and tail; tmc2a has no Bgee calls. Bulk calls are not hair-cell resolved and are not used for fate calls.

Protein / localization

• PMID:29269857
• Needs Tomt and Tmie for bundle targeting (PMID:28534737, PMID:30726219); does not need Lhfpl5 (PMID:32009898).

Function

• Alleles: TALEN PTC allele (Chou 2017; truncated 148 aa), cwr2 (5-bp del exon 7, in the double), cwr8, sa8817 (ENU nonsense).
• Lateral line: PMID:29269857
• Hearing unaffected in single mutant: PMID:29269857
• No paralog upregulation: PMID:29269857
• Vestibular: PMID:32371604
• Rescue of triple mutant by Tmc2b transgene (PMID:32371604) and of tmc2b sa8817 by Tmc2b-GFP (PMID:28534737).

Annotation decisions

• GO:0050910 IMP/IGI from Chou 2017 → MODIFY to GO:0050974 (lateral-line data; the single mutant hears normally).
• IEP development terms (inner ear morphogenesis, inner ear development, neuromast development) → REMOVE.
• NEW: stereocilium tip (IDA, PMID:29269857).