ctdspl2a notes

Provenance and setup

• Record: Q08BB5 (Swiss-Prot CTL2A_DANRE, 469 aa), ZFIN ZDB-GENE-061013-647, Ensembl ENSDARG00000061587 (chr25).
• Paralog: ctdspl2b (A4QNX6). DANRE_DUPLICATION batch 4 random pair (PANTHER TGD_tree; Ensembl
  Compara duplication node Osteoglossocephalai).
• Deep research was not available for this gene (Edison returned 402 Payment Required; the OpenAI
  key is invalid). Literature was searched by hand through Europe PMC (queries: ctdspl2a OR ctdspl2b;
  (CTDSPL2 OR SCP4) AND zebrafish; title search SCP4 OR CTDSPL2).
• No zebrafish study of either copy exists. The only hits for the zebrafish symbols are gene lists in
  a toxicology transcriptome paper and a human interactome paper; neither is informative.

Mammalian CTDSPL2 (SCP4)

• CTD phosphatase, chromatin-associated
  PMID:26920047
• FoxO1/3a phosphatase in liver; gluconeogenesis
  PMID:28851713
  PMID:28851713
• Domain organization; Smad1/5/8
  PMID:28506762
  PMID:28506762
• Catalytic motif; D293/D295
  PMID:35021089
  PMID:35021089
• Histone H3 Thr3 phosphatase
  PMID:42315649
• Cartilage (mouse, FoxO3a) PMID:38886174 and a 2026 review PMID:42208850 were read for
  background; not cited in the review.

My analysis (file:DANRE/ctdspl2a/ctdspl2a-bioinformatics/RESULTS.md)

• Protein: 70.9% identity between copies; FCP1-homology domain 97.5% (a) / 96.2% (b) identical to human;
  DxDx(T/V) motif DLDET conserved in both, aligned exactly to human D293-T297. The copies differ mainly in
  the N-terminal regulatory region. No relative-rate asymmetry (38 vs 38 changes).
• Expression: both maternal and ubiquitous; ctdspl2a two- to three-fold higher at every stage in
  E-ERAD-475; Bgee calls in the same 20+ tissues for both copies; gar CTDSPL2 also broad. No ZFIN records.

Annotation decisions

• MF IBA/IEA rows accepted (catalytic motif conserved). Nucleus IEA accepted.
• Positive regulation of gluconeogenesis (ARBA) kept as non-core: mammalian evidence is direct
  (FoxO dephosphorylation) but single-lab, and untested in fish.