sh3glb2b notes

Setup and provenance

• Fetched with just fetch-gene on A0A8M9Q303 (TrEMBL, RefSeq XP_021331719.1 "Endophilin-B2b
  isoform X1", 421 aa), the sh3glb2b accession with the most GOA rows (5: 4 IBA, 1 IEA; no PMID
  rows). The gene has 11 UniProt entries for RefSeq isoforms (e.g. Q802U5 / NP_957413.1, 373 aa);
  each other entry holds only 1 GOA row and none has experimental rows (checked with
  projects/DANRE_DUPLICATION/scripts/accession_audit.py, terminal output only). ZFIN
  ZDB-GENE-040426-833; Ensembl ENSDARG00000035470, chromosome 5 (plus an alternate-contig model
  ENSDARG00000109833).
• Deep research unavailable: Edison returned 402 Payment Required and the OpenAI key is
  invalid, so no -deep-research-*.md file exists. Literature searched by hand in Europe PMC
  (sh3glb2a, sh3glb2b, zebrafish AND (sh3glb2 OR "endophilin B2"), and mammalian
  endophilin-B2 searches). No zebrafish paper studies either copy.
• DANRE_DUPLICATION batch 4 (random draw, seed 20260928); paralog sh3glb2a. Compara duplication
  node Osteoglossocephalai; PANTHER call TGD_tree.

Zebrafish data

• Only expression: ZFIN curated wild-type in situ records (high-throughput screen,
  ZDB-PUB-040907-1) give sh3glb2b in central nervous system and eye/lens from segmentation
  to hatching stages, and sh3glb2a as whole-organism (ubiquitous-type) signal. See
  sh3glb2b-bioinformatics/RESULTS.md.

Mammalian endophilin-B2 (SH3GLB2)

• Identified as an SH3GLB1 partner; SH3GLB proteins form homo/heterodimers through a
  coiled-coil core and are cytoplasmic
  PMID:11161816
  PMID:11161816.
• N-BAR + SH3 architecture; mouse knockout viable; endosome maturation defects in cells
  PMID:28455444
  PMID:28455444
  PMID:28455444
  PMID:28455444.
• Mitophagy: heterodimer with endophilin-B1
  PMID:27112121.

IBA sources (sh3glb2b)

• endocytosis, membrane, membrane organization: node PTN009017136 (endophilin clade; donors
  include SH3GLB1 Q9Y371, mouse/rat endophilins, fly and worm endophilins).
• protein-macromolecule adaptor activity: node PTN009017043, a deeper node whose donors are
  human SORBS1 (Q9BX66) and two mouse genes; not an endophilin-specific assertion.
• sh3glb2a has none of these IBAs: every sh3glb2a UniProt entry is classified in PANTHER
  subfamily PTHR14167:SF68 "DREBRIN-LIKE PROTEIN-RELATED", while sh3glb2b is in SF106
  "ENDOPHILIN-B2 ISOFORM X1" (UniProt DR lines). The PANTHER v19 pair table used
  A0A8M6Z0F0 for sh3glb2a, which no longer resolves in UniProtKB (HTTP 404, 2026-09-28).

Pair analysis

See sh3glb2b-bioinformatics/RESULTS.md.